EP2227068A1 - Alternating transmission of electromagnetic radiation with two radiation sources - Google Patents

Abstract

The circuit arrangement has two radiation sources (5,13) for emitting radiations, and an energy store (3) which is coupled with the two radiation sources. A control device is arranged and equipped within the circuit arrangement such that the former radiation source is operated and the energy store is charged at the same time in an operating phase. Independent claims are also included for the following: (1) a smoke detector for detecting smoke with a radiation detector; (2) a building management system with a voltage source; and (3) a method for emitting electromagnetic radiation using circuit arrangement.

Description

The present invention generally relates to the technical field of danger detection technology and in particular to an energy-efficient control of radiation sources, which can be used in particular in a danger detector. The present invention relates in particular to a circuit arrangement for emitting electromagnetic radiation by means of two radiation sources, to a danger detector having such a circuit arrangement for detecting a dangerous situation and to a method for emitting electromagnetic radiation.

Optoelectronic hazard detectors include one or more optical transmitters that emit light and one or more receivers that receive the light affected by the quantity to be detected. The received signal is often very weak. The receiver is therefore sensitive to interference. The received signal is proportional to the light emitted by the transmitters. Thus, it would be desirable to emit as much light as possible. But these are limited by the available energy limits.

Particularly difficult is the operation of a hazard detector from batteries and / or batteries, as is the case in the case of wireless hazard detectors. Due to the limited performance of batteries and rechargeable batteries, low power consumption of the light source (s) of a battery and / or battery-powered hazard alarm is important to maximize maintenance intervals that typically require battery replacement or recharging.

However, a low power consumption is very important even when connected to a power supply line hazard detectors. In fact, power supply lines can be very long and accordingly have a correspondingly high line resistance. This is especially true because usually lines are used with a small cross-section, which are both cost-effective and can be easily laid on the other hand. Due to the line resistance, therefore, the current intensity of the current transmitted via the power supply line is limited. Furthermore, it should be noted that on such a power supply line usually very many detectors are connected, all of which are in operation at the same time and therefore must be supplied with electricity or fed at the same time.

A typical line for powering the peripheral hazard detectors of a hazard detection system is approximately 2000m long. The operating voltage of the center of the danger detection system is usually 24V. Due to the line resistance, the voltage left at the end of a long line can drop to 16V. More than 200 danger detectors can be connected to such a cable. For the operation of a single detector usually a current of only about 100μA is granted. The danger detectors must therefore work very energy-efficiently.

Light-emitting diodes emitting in the infrared range and commonly used in optoelectronic hazard detectors are operated at a forward voltage in the range of 1.6V. To achieve this voltage, a danger detector in a simple embodiment between the supply voltage and the light emitting diode on an element which limits the flow of current. At this current limiting element, the difference between the respective supply voltage and the forward voltage drops. In the example above, this difference is 14.4V (16V - 1.6V). If the average current in the light emitting diode is 100μA, then the power dissipation of the current limiting element will be 1440μW (14.4V x 100μA), whereas the electric power of the light emitting diode is only 160μW (1, 6V x 100μA). The electrical efficiency of the entire circuit within a hazard detector is thus only 10%.

In order to reduce the power loss within a hazard alarm, it is known to convert the voltage provided by the line to an intermediate voltage which is slightly higher than the required forward voltage of the light-emitting diode. For example, if the voltage were to be converted to 3.2V without losses and the current limiting element connected to this reduced voltage of 3.2V, then the power dissipation in the current limiting element would be 160μW ((3.2V-1.6V) x 100μA) and the power of the LED would also be 160μW (1.6V x 100μA). The efficiency would be at least 50% and the line would be 320μW or 20μA (320μW: 16V). This reduced power consumption could be exploited to connect even more hazard detectors to the line. However, it would also be possible to increase the current in the LED to, for example, 500 μA. The power dissipation in the current limiting element would then be 800μW (1.6V x 500μA) and the electric power of the LED would then also be 800μW ((3.2V-1.6V) x 500μA)). Together, this would result in a power draw of 1600μW and the current taken from the line would be 100μA (1600μW: 16V), as permitted by the maximum.

However, it is very complicated and difficult to build a voltage converter with the above-mentioned properties and in particular with the (almost) complete freedom from loss. In particular, it will hardly succeed to build a voltage converter, which has all the required properties and an efficiency of at least 50%. Such a voltage converter would be at least very expensive and would probably not be realized in a compact design, as would be desirable in danger detector.

The object of the present invention is a circuit arrangement having at least one radiation source create, which can be realized in a simple, compact and inexpensive and which has a high efficiency and thus a low power consumption.

This object is solved by the subject matters of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

In accordance with a first aspect of the invention, a circuit arrangement for emitting electromagnetic radiation is described. The circuit arrangement comprises (a) a first radiation source configured to emit a first radiation, (b) a second radiation source configured to emit a second radiation, (c) an energy store coupled to the first radiation source and the second radiation source, and (d) a control device which is arranged within the circuit arrangement and which is set up such that (d1) the first radiation source can be operated in a first operating phase and the energy store can be charged at the same time, and (d2) the second radiation source under a second operating phase Use of the energy stored in the first energy storage in the first phase of operation is operable.

The described circuit arrangement is based on the finding that the current flowing through the first radiation source can be used repeatedly by a suitable combination of the energy store with the two radiation sources, so that the efficiency of the circuit device becomes particularly high. Under the efficiency in this context, the ratio between (a) the radiant energy emitted by both radiation sources, and (b) the electrical energy which is supplied to the circuit arrangement. Since the circuit arrangement will typically be operated not clocked strictly continuous but clocked, can be in the determination of the efficiency of a suitable temporal Averaging should be made, the period considered should have at least a full period.

During the first operating phase, the second radiation source is preferably switched off. In a corresponding manner, the first radiation source can be switched off during the second operating phase.

2 # According to one embodiment of the invention, the control device has a first switching element. The first switching element may be a simple mechanical switch or in particular a semiconductor switching element such as an arbitrary transistor. By means of the first switching element, a current flow which is provided by a voltage source connected to the circuit arrangement can be controlled in a particularly simple way in accordance with the operating phases defined above.

The first switching element can be arranged and / or formed such that during the first operating phase of the energy storage is coupled to a terminal for a voltage source with which the described circuit arrangement is operable. During the second operating phase, the first switching element can disconnect a connection for a voltage source from the energy store, for example by simply opening a circuit, so that the second radiation source can be operated by the energy store without the use of an amount of current provided by the voltage source.

According to a further exemplary embodiment of the invention, at least one of the two radiation sources is an electro-optical converter and in particular an optoelectronic component. The electro-optical converter can in principle be a simple light bulb. The optoelectronic component can be, for example, a light-emitting diode or a semiconductor laser diode.

The two radiation sources can emit electromagnetic radiation of arbitrary wavelengths. Especially The electromagnetic radiation may in each case be light in the visible, in the infrared or in the ultraviolet spectral range. In addition to a comparatively narrow-band spectral range or even monochromatic radiation, the electromagnetic radiation may also have different wavelengths which represent a continuous spectrum or different separate narrowband and / or broadband spectral ranges.

The electromagnetic radiation may also have wavelengths associated with the far infrared and / or the far ultraviolet spectral range. Even microwave radiation or any other type of electromagnetic radiation can in principle be used as transmission radiation and correspondingly as first and / or second reception radiation. Correspondingly, the term "optically" is intended to refer to all the spectral ranges of electromagnetic radiation and by no means only to the visible spectral range.

According to a further exemplary embodiment of the invention, the first radiation has a first spectral distribution and the second radiation has a second spectral distribution, which is different from the first spectral distribution.

A different spectral distribution of the two radiations can be used, for example, in a smoke detector in an advantageous manner. Namely, the two different radiations can be scattered to different degrees depending on the size of the smoke particles to be detected, which are scattering centers for the respective radiation in a known manner. In this case, the scattering angle of the different spectral components can be different, so that information about the type and / or the nature of the smoke particles can be obtained by a suitable evaluation of different scatter signals. By repeatedly switching between the two radiation sources, various types of scattered light measurements can be carried out time and time again whose results, individually or in combination with each other, can provide information on the nature of the smoke and, if necessary, on the cause of the fire.

At this point, however, it should be noted that the two radiation sources can emit spectrally similar light to each other. The two identical radiations can then be used for the same purpose or for different purposes or measurements.

According to a further embodiment of the invention, the circuit arrangement additionally comprises (a) a first current limiting element which is connected in series with the first radiation source and / or (b) a second current limiting element which is connected in series with the second radiation source.

The use of one or more current-limiting elements has the advantage that damage to the first radiation source and / or to the second radiation source can be prevented as a result of excessive current flow. This is especially true when the time period for the first and / or for the second phase of operation is relatively long.

The first and / or the second current limiting element may be, for example, a choke coil. In particular, in a high-frequency operation of the described circuit arrangement, however, the inductance of a choke coil could turn out to be disadvantageous. Consequently, a simple ohmic resistor can also be used as the current limiting element. 6 # According to a further exemplary embodiment of the invention, the energy store has a capacitor. This means that at least part of the energy which is temporarily stored in the energy store is stored in the form of a charge accumulation in the capacitor. This means that during the first phase of operation thus a certain electrical Charge amount flows through the first radiation source and at the same time charges the energy storage. During the second phase of operation, the stored charge amount is at least partially used to operate the second radiation source.

Illustratively, one and the same amount of charge thus do twice a useful work. When flowing through the first radiation source during the first phase of operation, it provides for emission of the first radiation, during flow through the second radiation source during the second phase of operation, it ensures emission of the second radiation.

7 # According to a further exemplary embodiment of the invention, the control device has a second switching element.

The second switching element may likewise be a simple mechanical switch or, in particular, a semiconductor switching element such as, for example, an arbitrary transistor. By means of the second switching element, a current flow which is provided by the charged energy store can be provided in a particularly simple manner exclusively to the second radiation source.

In particular, by a synchronized actuation of the second switching element with the first switching element described above, a defined switching from the first operating phase to the second operating phase and vice versa can thus take place. In this case, the two different operating phases can follow one another directly in time or with a certain time interval.

8 # According to a further exemplary embodiment of the invention, the energy store has an inductance. The use of an inductance for the energy store has the advantage that a particular large energy can be stored temporarily in a built-up magnetic field by a simple current flow.

In the case of abrupt state changes, in particular when switching the first and / or the second switching element, harmful voltage peaks can be buffered, for example, by a so-called free-wheeling diode, thus preventing unwanted damage to individual components of the circuit arrangement. The function of a freewheeling diode can also be realized by a correspondingly polarized diode, which is connected on one side with the inductive energy storage and on the other side with a reference potential to which the two radiation sources are connected directly or indirectly.

If the second radiation source is a diode, then the rectifying property of the second radiation source can also be utilized in order to cushion voltage spikes on the inductance, which could possibly lead to damage of other components of the described circuit arrangement.

According to one embodiment variant of the invention, the two radiation sources are aligned and arranged relative to one another such that the first radiation and the second radiation at least partially form a common optical path.

This has the advantage that the two radiation sources can be viewed as a single pulsed radiation source. The pulsed radiation source has a particularly high efficiency due to the above-described double utilization of the amount of current flowing (a) first through the first radiation source and into the energy storage and (b) then released from the energy storage and flowing through the second radiation source. This can result in a variety of applications for the circuit described, in which it depends in particular on a highly efficient conversion of electrical energy into radiation.

It should be noted that it is by no means necessary that the beam paths of the first and the second radiation are completely superimposed. Rather, enough in many Already a certain spatial overlap between the first and the second radiation to effectively start from a common optical path.

It is further pointed out that two initially different optical paths can be combined in a known manner by the use of a beam splitter or a beam merger. A particularly efficient beam combination can also be achieved by the use of optical components whose refractive properties, their transmission and / or their reflection depend on the respective wavelength, polarization of the first and / or the second radiation.

According to a further embodiment variant of the invention, the two radiation sources are aligned and arranged relative to one another such that (a) the first radiation defines a first optical path and (b) the second radiation defines a second optical path, wherein the second optical path is spatially different to the first optical route.

Thus, for example, in a smoke detector in a volume to be monitored or in a scattering volume, the first radiation separated from the second radiation occur. Depending on the spatial arrangement and an optionally time-dependent activation of one or more radiation receivers, with which or from the volume of emerging radiation is detected, the respective emerging and in particular in the volume scattered radiation along a common exit line or alternatively along two separate optical exit routes leave the volume. This can mean that the first measuring light resulting from the first radiation and the second measuring light resulting from the second radiation are received or evaluated separately or jointly.

9 # According to a further embodiment of the invention, the first radiation source and / or the second radiation source at least two transmitting elements. The realization of the first and / or the second radiation source with a plurality of individual transmission elements has the advantage that in a simple and inexpensive way, a highly efficient radiation source can be constructed, the available energy is particularly well utilized. In this case, the individual transmission elements can be combined in a series and / or in a parallel circuit. The transmitter elements combined with one another are preferably arranged relative to one another in such a way that their transmitted transmission partial beams overlap as possible and thus lead to intensive radiation.

Preferably, the first and / or the second radiation source each have a certain number of light emitting diodes, which may be electrically connected in series. These series-connected light-emitting diodes can be arranged so that the emitted light from each of a group of light-emitting diodes substantially coincides and is used to operate the same optical path.

According to a further aspect of the invention, a danger detector for detecting a dangerous situation is described. The hazard detector has a circuit arrangement of the type described above.

The danger alarm described is based on the finding that the circuit arrangement described above can be used in particular for its high energy efficiency in an advantageous manner for a danger detector, which may only have a very low power consumption and still sufficient radiation is available to the dangerous situation reliably to detect.

The high energy efficiency leads advantageously to a low heat development within the hazard alarm. As a result, electronic components of the hazard alarm can be operated without cooling in a comparatively cool and thermally stable environment. This may cause the noise of the affected Components are kept low, so that without a significant increase in a false alarm rate of the hazard can be optimized in terms of high sensitivity.

The danger detector can be, for example, a so-called presence detector. In this case, the first and / or the second radiation source can be associated with a reflex light barrier, which is directed against an object to be monitored. The light emitted by the radiation source is then reflected and impinges on a radiation receiver. As soon as the object is removed, the received signal disappears and the presence detector triggers an alarm. As a result, for example, the unauthorized opening a door or the unauthorized removal of a valuable object can be reliably detected.

The mode of operation of the danger detector can be based on the so-called transillumination principle. In this case, for example, the radiation emitted by or from the radiation source (s) passes through a container which is filled with a substance which changes its optical properties in the presence of hazardous gases. As a result, the intensity of the transmitted radiation received by a radiation receiver also changes and the detector can trigger an alarm.

The circuit arrangement described above can be used in a particularly advantageous manner for a hazard detector, which is adapted to detect smoke and therefore can be referred to as a smoke detector. The smoke detector can work, for example, according to the known optical scattered light principle. It is assumed that in the event of a danger, for example, smoke particles will enter the spreading volume of the hazard alarm due to undesired smoke development and / or the formation of a fire. The radiation emitted by the radiation source or by the radiation sources is then scattered back by these particles. A part This light falls on a radiation receiver of the danger detector and triggers an alarm.

11 # According to another aspect of the invention, a smoke detector for detecting smoke is described. The smoke detector comprises (a) a circuit of the type described above for emitting electromagnetic radiation and (b) at least one radiation detector for receiving electromagnetic radiation generated in the event of at least partial scattering of the emitted electromagnetic radiation on the smoke.

The danger detector described is based on the finding that the circuit arrangement described above can be advantageously used for a danger detector, in particular because of its high energy efficiency. Furthermore, the radiations of both radiation sources, which are appropriately arranged in the circuit arrangement and activated alternately to achieve high energy efficiency, can be advantageously used to activate spatially different optical paths with the two radiation sources and / or different spectral distributions of the first Radiation compared to the second radiation to realize. It may be of great advantage that due to the law of conservation of the charge quantities in a stationary operation of the circuit arrangement, the two currents that flow through the first radiation source and the second radiation source are always the same. If the two radiation sources have an equally high radiation yield, then it is automatically ensured in this way that the first radiation and the second radiation have at least on average an equal radiation intensity.

In accordance with an embodiment of the invention, the smoke detector additionally has a temperature sensor and an evaluation unit, which is coupled directly or indirectly to at least the radiation detector and the temperature sensor. The The evaluation unit is set up in such a way that an alarm message can be initiated based on a first measurement signal generated by the radiation detector and a second signal generated by the temperature sensor.

Such a smoke detector may be, for example, a so-called. Multi-criteria fire alarm, in which an alarm message based not only on a detection of smoke but also on the detection of a change in temperature and in particular a temperature increase. Due to the high efficiency of the circuit arrangement used with respect to the conversion of electrical energy into radiant energy and the associated only very low heat generation, the temperature measurement can be performed with high accuracy largely undisturbed by the operation of the circuit. In this way, a particularly sensitive temperature measurement and in combination with the smoke detection, which is carried out for example by a scattered light measurement, a sensitive and on the other hand afflicted with a low false alarm rate fire detection can be ensured.

In another aspect of the invention, a system is described which comprises (a) a central station having a voltage source, (b) a supply line coupled to the voltage source, and (c) at least one circuit arrangement of the type described above connected to the supply line is.

The described system, which may be, for example, a building management system, is based on the finding that the above-described circuit arrangement for emitting electromagnetic radiation also has a high efficiency with respect to the conversion of electrical energy into radiant energy, if the difference between the supply voltage of the voltage source and the voltage required to operate the first and / or the second radiation source is particularly large. This voltage difference can, in particular with a long supply line, to which a plurality of circuit arrangements or other electrical loads are connected, be different for one and the same circuit arrangement at different points of the supply line.

Typically, the respective voltage drop depends on a total power requirement, which is determined by the number of connected electrical loads. The loads may be circuit arrangements of the type described above or other electrical loads. The voltage drop also depends on the line resistance of the supply line, which in turn is determined by the resistivity of the line material and the line cross section.

By suitable dimensioning of the electronic components of the circuit arrangement and / or by a suitable timing, the effective voltage drop in each circuit arrangement can be adjusted, so that a particularly effective conversion of electrical energy into electromagnetic radiation is ensured.

In particular, the above-mentioned building management system can be a danger notification system which can be used to detect a dangerous situation, for example within a monitored building. The use of the circuit arrangement described above in detail for individual peripheral devices of the danger detection system offers great advantages, in particular, when the danger detection system is a smoke detection system. With regard to the advantages which the use of the circuit arrangement for emitting electromagnetic radiation in connection with a smoke detector offers, reference is made to the above-mentioned advantages of the smoke detector, which optionally may have a temperature sensor.

14 # According to a further aspect of the invention, a method for emitting electromagnetic radiation is described. The method is particularly using a Circuit arrangement of the type described above feasible. The method comprises (a) during a first phase of operation, emitting a first radiation by means of a first radiation source and simultaneously charging an energy store, and (b) during a second phase of operation, emitting a second radiation by means of a second radiation source using one in the first operating phase previously stored in the energy storage energy.

The method described is based on the knowledge that the current flowing through the first radiation source during the first operating phase can not only be used to operate the first radiation source. Rather, an energy associated with this current flow can be temporarily stored in the energy store and used during the second operating phase to operate the second radiation source. Due to this dual use, without the use of either very expensive or very energy-inefficient voltage transformers, the radiation sources can also be operated on a voltage supply which provides an increased supply voltage in comparison to the voltage levels actually required by the radiation sources. The conversion of electrical energy into electromagnetic radiation can thus be realized with a particularly high efficiency.

According to a further embodiment of the invention, (a) a first resting phase is provided between the first operating phase and the second operating phase during which the two radiation sources are deactivated, and / or (b) a second one between the second operating phase and the first operating phase Rest phase provided during which the two radiation sources are disabled.

The use of at least one rest within an operating cycle of the circuit arrangement described above has the advantage that the two radiation sources can be subjected to a current flow in the respective operating phase, whose current is greater than a current that would endure the radiation source in question in a continuous operation. In this way, on the one hand generates a particularly intense radiation and on the other hand, a thermal damage to the radiation source (s) can be prevented.

Another advantage with regard to the use of rest breaks can be that the amplification of signals, which supply power to the two radiation sources, is considerably simplified. In particular, in the event that the periods of the two operating phases are each at least approximately the same length and taking into account a charge retention, according to which the current in the steady state, the current must be the same size as the current in the second phase of operation, an amplifier circuit for the namely, amplify two sources of radiation in an advantageous manner, namely only an alternating current without a DC component.

The term "deactivated" in this context means that the radiation source in question does not emit electromagnetic radiation.

It should be noted that embodiments of the invention have been described with reference to different subject matters. In particular, some embodiments of the invention are described with apparatus claims and other embodiments of the invention with method claims. However, it will be readily apparent to those skilled in the art upon reading this application that, unless explicitly stated otherwise, in addition to a combination of features belonging to a type of subject matter, any combination of features that may result in different types of features is also possible Subject matters belong.

• Figur 1 zeigt gemäß einem Ausführungsbeispiel der Erfindung eine Schaltungsanordnung mit zwei Schaltelementen und einem als Kondensator ausgebildeten Energiespeicher.
• Figur 2 zeigt die wesentlichen optoelektronischen Elemente eines Gefahrenmelders, welcher auf dem Prinzip einer Lichtschranke beruht.
• Figur 3 zeigt in einem Zeitdiagramm die Funktionsweise eines Gefahrmelders mit den in Figur 2 dargestellten optoelektronischen Elementen.
• Figur 4 zeigt die wesentlichen optoelektronischen Elemente eines Gefahrenmelders mit zwei getrennten optischen Pfaden.
• Figur 5 zeigt in einem Zeitdiagramm die Funktionsweise eines Gefahrmelders mit den in Figur 4 dargestellten optoelektronischen Elementen.
• Figur 6 zeigt die wesentlichen optoelektronischen Elemente eines Gefahrenmelders mit zwei optischen Pfaden, die teilweise voneinander getrennt sind und teilweise zusammen verlaufen.
• Figur 7 zeigt in einem Zeitdiagramm die Funktionsweise eines Gefahrmelders mit den in Figur 6 dargestellten optoelektronischen Elementen.

Other advantages and features of the present invention will become apparent from the following exemplary description preferred embodiments. The individual figures of the drawing of this application are merely to be regarded as schematic and not to scale.

• FIG. 1 shows according to an embodiment of the invention, a circuit arrangement with two switching elements and designed as a capacitor energy storage.
• FIG. 2 shows the essential optoelectronic elements of a hazard detector, which is based on the principle of a photoelectric sensor.
• FIG. 3 shows in a time chart the operation of a hazard detector with the in FIG. 2 represented optoelectronic elements.
• FIG. 4 shows the essential optoelectronic elements of a hazard detector with two separate optical paths.
• FIG. 5 shows in a time chart the operation of a hazard detector with the in FIG. 4 represented optoelectronic elements.
• FIG. 6 shows the main optoelectronic elements of a hazard detector with two optical paths, which are partially separated and partially together.
• FIG. 7 shows in a time chart the operation of a hazard detector with the in FIG. 6 represented optoelectronic elements.

It should be noted at this point that the same or corresponding components in the drawing in the various figures are given the same reference numerals.

It should also be noted that the embodiments described below only a limited selection of possible embodiments of the invention represent. In particular, it is possible to suitably combine the features of individual embodiments with one another, so that a multiplicity of different embodiments are to be regarded as obviously disclosed to the person skilled in the art with the embodiment variants explicitly illustrated here.

FIG. 1 shows according to an embodiment of the invention, a circuit arrangement with two switching elements 2 and 11 and designed as a capacitor energy storage. 3

A first switching element 2, which is also referred to below simply as a first switch, is connected to the first terminal of a voltage source 1 and to the first terminal of an energy store 3. According to the exemplary embodiment illustrated here, the second terminal of the energy store 3 leads via a current limiting element 4 to a first radiation source 5, which is also referred to below as an optical transmitter 5. It should be noted that the use of the current limiting element 4, which is a simple ohmic resistance according to the exemplary embodiment illustrated here, is optional and that the energy store 3 can also be connected directly to the first terminal of the first optical transmitter 5. The second terminal of the optical transmitter 5 is connected to a reference potential 6, to which also the second terminal of the voltage source 1 is connected. When the first switch 2 is closed, then the electric circuit via the first optical transmitter 5 is closed.

A second switching element 11 or a second switch 11 is connected with its first terminal to the first terminal of the energy accumulator 3 and with its second terminal to the reference potential 6. The first terminal of a second optical transmitter 13 is connected to the reference potential 6. The second connection is optional via a current limiting element 12 to the second terminal of Energy storage 3 connected. The circuit via the second optical transmitter 5 is then closed when the second switch 11 is closed.

The optical transmitters 5 and 13 are in the embodiment described here such that the current can flow only in one direction. More specifically, the first transmitter 5 is connected so that a current can flow in it only when the first switch 2 is closed. The second transmitter 13 is connected so that a current can flow in it only when the second switch 11 is closed.

In a first operating phase, the switch 2 is closed and the switch 11 is open, so that current flows from the voltage source 1 through the first optical transmitter 5 in the manner described above. In this first operating phase of the energy storage 3 is charged. It is assumed that immediately after closing the switch 2, the voltage across the energy storage device 3 designed as a capacitor changes so fast that the AC impedance of the capacitor 3 can be neglected, at least at the beginning of the first phase of operation.

In a second operating phase, the switch 2 is open and the switch 11 is closed so that in the manner described above, current flows from the electrical energy store 3 through the second optical transmitter 13. As a result, the electrical energy storage 3 is at least partially discharged.

If the current limiting element 4 is designed so that averaging time 100μA flows through the first transmitter, then a current of 100μA or an output of 1600μW is taken from the voltage source 1 on average at an operating voltage of 16V. If the first optical transmitter 5 is a light emitting diode with a forward voltage of 1.6V, then the electrical power consumed by it will be 160μW. As already indicated above, in accordance with the exemplary embodiment described here, the electrical energy store Capacitor 3 and the current limiting element is a resistor 4.

In the second operating phase of the energy storage 3 is partially or completely discharged. The amount of charge that has flowed through the first transmitter 5 in the first phase now flows through the second transmitter 13. The two charge quantities and thus the current flowing in the mean time are the same according to the principle of conservation of charges, and the energy in the second transmitter is again 160μW. The total power consumption of the two optical transmitters 5 and 13 is thus 320 μW. The electrical efficiency of the circuit shown is under the circumstances shown at 20%.

However, the efficiency of the entire circuit can be easily further improved by the first optical transmitter 5 is not made of a single but of several series-connected light-emitting diodes. These light emitting diodes may be arranged geometrically such that the light emitted by them substantially coincides. Likewise, the second optical transmitter 13 can be composed of a plurality of light-emitting diodes. If, for example, the two optical transmitters 5 and 13 consist of two series-connected LEDs, the total forward voltage is 3.2V in each case. Now, if the average current in the first optical transmitter 5 is again limited to 100μA, then the converted in the first transmitter electrical power is 320μW. The voltage drop across the second transmitter 13 is then also 3.2V, and the power is also 320μW. The total power converted in the transmitters is now 640μW.

However, since the power consumed from the line or from the voltage source 1 with a voltage of 16V is still 1600 μW, the efficiency of the entire circuit arrangement improved by the series connection of two light-emitting diodes in each case is now 40%. This value is similar to the one used in the introduction to the description above described voltage converter, which reduces the supply voltage to 3.2V and can be built but only with great difficulty.

It should be noted that the energy storage 3 can also be realized by means of an inductance. By using an inductance, the circuit becomes even easier, namely, even after the opening of the switch 2 due to the self-inductance and the so-called Lenz's rule, a current will continue to flow through this inductance and the corresponding voltage across the inductance will be so will adjust that this current actually flows. However, if only the first switch 2 is opened and the second switch 11 is not closed at the same time, then the voltage across the inductance may increase so much that current still flows along any one of the current paths. As a result, one of the components located on the relevant current path can easily penetrate due to the increased voltage. This is of course undesirable and can be prevented, for example, by using instead of the switch 11 a correspondingly polarized diode or by taking advantage of the fact that the optical transmitter 13 also has the rectifying character of a diode. In this case, however, the circuit arrangement must be adapted so that after opening the switch 2, the current can flow automatically through the second optical transmitter 13. Of course, the self-inductance and the current induced by the self-inductance of the coil and its current direction must be taken into account in accordance with Lenz's rule. This can be done by a suitable polarity reversal of the formed as an inductance energy storage 3, which can be realized for example using suitable switches. It must be ensured in any case that in the second phase of operation no current flows through the diode, which instead of the switch 11 in the in FIG. 1 shown circuit arrangement is installed.

FIG. 2 shows the essential optoelectronic elements of a hazard detector, which is based on the principle of a photoelectric sensor. The hazard detector has a first optical transmitter 21, which can emit a first light 22. The detector has a second optical transmitter 23 which can emit a second light 24. The two optical transmitters 21 and 23 are arranged so that the emitted light 22 and 24 largely coincides and thus produces a luminous flux of double intensity. This luminous flux is reflected or scattered by an object 29 to be monitored, and reaches an optical receiver 25 as measuring light 26.

FIG. 3 shows in a time chart the operation of a hazard detector with the in FIG. 2 represented optoelectronic elements.

A curve 31 corresponds to the time profile of the electric current flowing through the first optical transmitter 21. This current 31, which is directly proportional to the light emitted by the first optical transmitter 21, reaches its maximum intensity in a first operating phase 34. In the remaining time, this current 31 is very small.

A curve 32 corresponds to the time profile of the electric current flowing through the second optical transmitter 23. This current 32, which is directly proportional to the light emitted by the second optical transmitter 23, reaches its maximum intensity in a second operating phase 36. In the rest of the time, and in particular in the first operating phase 34, this current 32 is very small.

According to the exemplary embodiment illustrated here, there are resting phases 35 and 37 between the active operating phases 34 and 36.

The luminous flux emitted by the two optical transmitters 21, 23 together is approximately the same in the two active operating phases 34, 36. But often it will not always be exactly the same size as a result of statistical fluctuations and other contingencies. As a result, the backscattered light detected by the optical receiver 25 is similar but not exactly the same in the two active phases of operation, in most cases. This light is generated in the optical receiver which is in FIG. 2 is designated as 25, a current waveform 33. This current waveform 33 can be amplified by a suitable circuit, not shown, and optionally used to trigger an alarm message.

The electrical amplifier, which is connected downstream of the optical receiver 25, can be constructed particularly simply if it has to amplify a rectangular signal with a duty cycle of about 50%. This is the case when the lengths of the phases 34, 35, 36 and 37 are approximately equal. The frequency of the current to be amplified is twice the repetition frequency of the current in one of the two optical transmitters.

If the above-described condition is not satisfied, then it may be more difficult to amplify the current generated in the optical receiver 25. With a corresponding effort, it will still be possible. In particular, the amplification can be difficult to realize when the resting phases 35 and 37 are omitted, because in this case essentially a direct current must be amplified.

FIG. 4 shows the essential optoelectronic elements of a hazard detector with two separate optical paths. The danger detector may be, for example, a fire detector with a smoke chamber and a reference chamber. The two chambers are typically the same structure and subject to the same environmental influences. The Smoke chamber is open against the environment, so that smoke can penetrate. The reference chamber, on the other hand, is closed, so that a (reference) measurement takes place without the influence of smoke.

The danger detector has, for example, in the smoke chamber on a first optical transmitter 41, the light 42 emits. This light 42 is deflected as a result of smoke 49a and possibly other influences and passes as a measuring light 44 in the first receiver 43. The hazard detector includes, for example in the reference chamber, a second optical transmitter 45, the light 46 emits. This light 46 is also deflected as a result of various influences, such as a reference scattering object 49b, but not as a result of smoke, and enters the second receiver 47 as measurement light 48.

FIG. 5 shows in a time chart the operation of a hazard detector with the in FIG. 4 represented optoelectronic elements. A curve 51 corresponds to the time profile of the electric current through the first optical transmitter 41 and thus also the intensity of the emitted first light 42. This current 51 reaches its maximum strength in a first operating phase 55. In the remaining time, this current 51 is very small , A curve 52 corresponds to the time profile of the current in the first receiver 43 as a result of the received measuring light 44. This time curve 52 essentially corresponds to the time profile of the current 51. The strength of the measured current 52 results from the optical conditions in FIG smoke chamber.

A curve 53 corresponds to the time profile of the electric current through the second optical transmitter 45 and thus also the intensity of the emitted second light 46. This current 53 reaches its maximum intensity in a second operating phase 57. In the remaining time and in particular in the first operating phase 55, this current 53 is very small. Resting phases 56 and 58 can be inserted between the active operating phases 55 and 57 be in which none of the optical transmitter is energized.

A curve 54 corresponds to the time profile of the current in the second optical receiver 47. The time profile of the current 54 substantially corresponds to the time profile of the current 53 through the second optical transmitter 45. The strength of the current 54 generated by the second optical receiver results due to the conditions, especially in the reference chamber.

The received signals corresponding to curves 52 and 54 are amplified and appropriately linked together. For example, the difference or the quotient of these two signal profiles 52 and 54 can be calculated by means of an evaluation unit. If the result of the link reaches certain limits, the hazard detector can trigger an alarm.

FIG. 6 shows the main optoelectronic elements of a hazard detector with two optical paths, which are partially separated and partially together. The hazard detector may be, for example, a smoke detector in which the penetrated smoke is illuminated at two different angles.

The detector has a first optical transmitter 61, which emits light 62 having a first spectral distribution. This light 62 is deflected as a result of smoke 69, but also from other influences. A portion of this light 62 passes as part of a measuring light 66 into an optical receiver 65. The detector includes a second optical transmitter 63 which emits a second light 64 having a second spectral distribution, which may be different from the first spectral distribution. This second light 64 is also deflected as a result of the smoke 69, among other things. A portion of this light 64 also enters the optical receiver 65 as part of the measurement light 66.

FIG. 7 shows in a time chart the operation of a hazard detector with the in FIG. 6 represented optoelectronic elements.

A curve 71 corresponds to the time profile of the electric current through the first optical transmitter 61. This current 71 and thus also the intensity of the first light 62 reaches its maximum intensity in a first operating phase 74. In the remaining time, this current is very small. Correspondingly, a curve 72 corresponds to the time profile of the electric current through the second optical transmitter 63. This current 72 and thus also the intensity of the second light 64 reaches its maximum intensity in a second operating phase 76. In the rest of the time and in particular in the In the first operating phase 74, this current is very small. Between the active operating phase 74 and 76 may optionally be the two resting phases 75 and 77 are located, in which neither of the two optical transmitters is subjected to a current.

A curve 73 corresponds to the time profile of the current generated by the receiver 65. The time profile of this current 73 essentially corresponds to the time profile of the currents 71 and 72. The strength of the received current may possibly be greatly different in the two active operating phases 74 and 76.

The received signals corresponding to the curve 73 are amplified and further processed in a suitable and known manner. By comparing the signal in the two active operating phases 74 and 76, for example, conclusions about the type of a detected fire are possible.

1

Spannungsquelle

2

erstes Schaltelement / erster Schalter

3

Energiespeicher / Kondensator

4

Strombegrenzungselement / Widerstand

5

erste Strahlungsquelle / erster optischer Sender

6

Bezugspotential / Massepotential

11

zweites Schaltelement / zweiter Schalter

12

Strombegrenzungselement / Widerstand

13

zweite Strahlungsquelle / zweiter optischer Sender

21

erste Strahlungsquelle / erster optischer Sende

22

erste Strahlung / erstes Licht

23

zweite Strahlungsquelle / zweiter optischer Sender

24

zweite Strahlung / zweites Licht

25

Strahlungsempfänger / optischer Empfänger

26

Messlicht

29

Objekt

31

Stromverlauf durch ersten optischen Sender

32

Stromverlauf durch zweiten optischen Sender

33

Stromverlauf in optischen Empfänger

34

erste Betriebsphase

35

erste Ruhephase

36

zweite Betriebsphase

37

zweite Ruhephase

41

erster optischer Sender

42

erstes Licht

43

erster optischer Empfänger

44

Messlicht

45

zweiter optischer Sender

46

zweites Licht

47

zweiten optischen Empfänger

48

Messlicht

49a

Rauch

49b

Referenzstreuobjekt

51

Stromverlauf durch ersten optischen Sender

52

Stromverlauf in erstem optischen Empfänger

53

Stromverlauf durch zweiten optischen Sender

54

Stromverlauf in zweitem optischen Empfänger

55

erste Betriebsphase

56

erste Ruhephase

57

zweite Betriebsphase

58

zweite Ruhephase

61

erster optischer Sender

62

erstes Licht

63

zweiter optischer Sender

64

zweites Licht

65

optischer Empfänger

66

Messlicht

69

Rauch

71

Stromverlauf durch ersten optischen Sender

72

73

Stromverlauf durch zweiten optischen Sender

74

erste Betriebsphase

75

erste Ruhephase

76

zweite Betriebsphase

77

zweite Ruhephase

LIST OF REFERENCE NUMBERS

1

voltage source

2

first switching element / first switch

3

Energy storage / capacitor

4

Current limiting element / resistor

5

first radiation source / first optical transmitter

6

Reference potential / ground potential

11

second switching element / second switch

12

Current limiting element / resistor

13

second radiation source / second optical transmitter

21

first radiation source / first optical transmitter

22

first radiation / first light

23

second radiation source / second optical transmitter

24

second radiation / second light

25

Radiation receiver / optical receiver

26

measuring light

29

object

31

Current flow through the first optical transmitter

32

Current flow through the second optical transmitter

33

Current flow in optical receiver

34

first operating phase

35

first resting phase

36

second operating phase

37

second rest phase

41

first optical transmitter

42

first light

43

first optical receiver

44

measuring light

45

second optical transmitter

46

second light

47

second optical receiver

48

measuring light

49a

smoke

49b

Reference scattering object

51

Current flow through the first optical transmitter

52

Current flow in the first optical receiver

53

Current flow through the second optical transmitter

54

Current flow in second optical receiver

55

first operating phase

56

first resting phase

57

second operating phase

58

second rest phase

61

first optical transmitter

62

first light

63

second optical transmitter

64

second light

65

optical receiver

66

measuring light

69

smoke

71

Current flow through the first optical transmitter

72

73

Current flow through the second optical transmitter

74

first operating phase

75

first resting phase

76

second operating phase

77

second rest phase

Claims (15)

Circuit arrangement for emitting electromagnetic radiation (22, 24) having the circuit arrangement A first radiation source (5, 21) arranged to emit a first radiation (22), A second radiation source (13, 23) arranged to emit a second radiation (24), An energy store (3), which is coupled to the first radiation source (5, 21) and the second radiation source (13, 23), and A control device (2, 11) which is arranged within the circuit arrangement in such a way and which is set up such that - In a first phase of operation (34) the first radiation source (5, 21) operable and at the same time the energy storage device (3) is chargeable and - In a second phase of operation (36), the second radiation source (13, 23) is operable using the energy stored in the first energy storage (3) in the first operating phase. Circuit arrangement according to the preceding claim, wherein the control device comprises a first switching element (2). Circuit arrangement according to one of the preceding claims,
in which
at least one of the two radiation sources is an electro-optical converter and in particular an optoelectronic component (5, 21, 13, 23). Circuit arrangement according to one of the preceding claims,
in which
the first radiation (22) has a first spectral distribution and
the second radiation (24) has a second spectral distribution which is different from the first spectral distribution. Circuit arrangement according to one of the preceding claims, additionally comprising A first current limiting element (4) which is connected in series with the first radiation source (5, 21) and / or A second current limiting element (12) which is connected in series with the second radiation source (13, 23). Circuit arrangement according to one of the preceding claims,
in which
the energy store has a capacitor (3). Circuit arrangement according to one of the preceding claims,
in which
the control device has a second switching element (11). Circuit arrangement according to one of the preceding claims,
in which
the energy store has an inductance. Circuit arrangement according to one of the preceding claims,
wherein the first radiation source (5, 21) and / or the second radiation source (13, 23) has at least two transmitting elements. Danger detector for detecting a dangerous situation, having the danger detector • A circuit arrangement according to one of the preceding claims. Smoke detector for detecting smoke, the smoke detector having A circuit arrangement according to one of claims 1 to 9 for emitting electromagnetic radiation (22, 24) and • at least one radiation detector (25) for receiving electromagnetic radiation (26) which is generated in the case of at least partial scattering of the emitted electromagnetic radiation (22, 24) on the smoke (29). Smoke detector according to claim 11, additionally comprising • a temperature sensor and An evaluation unit, which is coupled directly or indirectly to at least the radiation detector and the temperature sensor, wherein the evaluation unit is set up such that an alarm message can be initiated based on a first measurement signal generated by the radiation detector and a second signal generated by the temperature sensor. Comprising system A central station with a voltage source, • a supply line coupled to the voltage source and At least one circuit arrangement according to one of the preceding claims, which is connected to the supply line. A method for emitting electromagnetic radiation (22, 24), in particular using a circuit arrangement according to one of claims 1 to 9, comprising the method During a first operating phase, emitting a first radiation by means of a first radiation source and simultaneous charging of an energy store, and During a second operating phase (36), emitting a second radiation (24) by means of a second radiation source (13, 23) using energy previously stored in the energy store (3) in the first operating phase (34). A method according to the preceding claim, wherein - Between the first operating phase (34) and the second operating phase (36) is provided a first resting phase (35) during which the two radiation sources (5, 21, 13, 23) are deactivated, and / or - a second resting phase (37) is provided between the second operating phase (36) and the first operating phase (34), during which the two radiation sources (5, 21, 13, 23) are deactivated.

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