Smoke detection unit for optical smoke detection based on the two-color principle, comprising a light-emitting diode with LED chip and light converter, as well as a suitable smoke detector.

Abstract

The invention relates to a smoke detection unit (10) for optical smoke detection based on the two-color principle, comprising a light-emitting diode (LED) (1) for light emission in a first and second wavelength range, an LED chip (3), and a light converter (4) with a phosphorescent phosphor having a luminescence time constant (τ). The smoke detection unit includes a photosensor (2) and a control unit (6), which is configured to activate the LED by means of an electrical test pulse (ETI) with a test on-time (T). TON) to control the LED in a range of 0.02 to 0.2 times the phosphor's illumination time constant, to determine a first light intensity value (1L) from a detected photosensor signal (PS) during the test on-time, subsequently to control the LED by means of a longer electrical charging pulse (EAI) to optically charge the phosphor, and to determine a second light intensity value (2L) at the end of the charging on-time (T). AON ) or at the beginning of the charging / off period (T AOFF ) to determine from the photosensor signal, to form a two-color ratio or a two-color difference from the first and second light intensity values, and to take this or these into account in the fire alarm (AL).

Description

[0001] The invention relates to a first and second smoke detection unit for optical smoke detection according to the two-color principle. The smoke detection unit comprises a light-emitting diode with (only) one LED chip for emitting light in a first wavelength range, as well as a light converter for converting a portion of the emitted light into light in a second wavelength range. The light converter comprises a phosphorescent phosphor with a luminous time constant. The smoke detection unit also comprises a photosensor spectrally tuned to the light emitted by the light-emitting diode, and a control unit connected to the light-emitting diode and the photosensor. The control unit is configured to form a two-color ratio or a two-color difference from a detected sensor signal of the photosensor and to take this or these into account when triggering a fire alarm.The photosensor is in particular a photodiode, preferably a silicon photodiode or silicon PIN photodiode.

[0002] Furthermore, the invention relates to a scattered light smoke detector, an extinction smoke detector and an open scattered light smoke detector, each with a smoke detection unit according to the invention.

[0003] From EP 3 574 530 B1 and EP 3 276 680 A1 by the applicant, an arrangement for optical smoke detection based on the two-color principle is known. The arrangement comprises a light-emitting diode and a photosensor for detecting scattered light or transmitted light. The light-emitting diode is designed to emit light in a first wavelength range and in a different second wavelength range. According to the invention therein, the light-emitting diode has an LED chip for emitting light in the first wavelength range and a light converter for converting a portion of the emitted light into light in the second wavelength range. The second wavelength range has a spectral half-width of a maximum of 100 nm. By appropriately evaluating the two scattered light intensities detected by the photosensor, a distinction between smoke, dust, and water vapor is possible according to the two-color ratio principle.This can prevent a possible false alarm from being issued during smoke detection.

[0004] Based on this, it is an object of the invention to provide an alternative first and second smoke detection unit for optical smoke detection.

[0005] It is a further object of the invention to provide a suitable scattered light smoke detector, extinction smoke detector and a suitable open scattered light smoke detector, each having such a smoke detection unit.

[0006] Advantages and embodiments of the invention, which can be used individually or in combination with one another, are the subject of the dependent claims.

[0007] According to the invention, for the first smoke detection unit, the control unit is configured to control the light-emitting diode by means of an electrical test pulse with a test period to emit a time-associated test light pulse. The test period is comprised of a test on-time and a subsequent test off-time. The test on-time is preferably in a range of 0.02 to 0.2 times the luminous flux constant of the phosphor. Furthermore, the control unit is configured to determine a first light intensity value during the test on-time of the electrical test pulse from a detected sensor signal of the photosensor, i.e. from a detected photosensor signal. The control unit is configured to subsequently control the light-emitting diode by means of an electrical charging pulse to emit a time-associated charging light pulse in order to optically charge the phosphor.The electrical charging pulse has a charging duty cycle that is greater than the luminous flux constant of the phosphor. Furthermore, the control unit is configured to determine a second light intensity value at the end of the charging duty cycle or at the beginning of the charging off cycle of the electrical charging pulse from the sensor signal, to further form a two-color ratio or a two-color difference from the first light intensity value and the second light intensity value, and finally to consider the two-color ratio or the two-color difference when triggering the fire alarm.

[0008] Due to the comparatively long optical charging time, a second light intensity value corresponding to the received red or infrared value is available with a high signal level during the subsequent charging / off period of the electrical charging pulse. This advantageously enables more precise measurement of the second light intensity value.

[0009] The light-emitting diode has (only) one LED chip for emitting typically monochromatic light. The first wavelength range preferably extends from 315 nm to 490 nm. Spectrally, this corresponds to the optical range from near ultraviolet light (UV-A) to blue-green light. The second wavelength range preferably extends from 640 nm to 1400 nm. This corresponds to the optical range from red / orange light to near infrared light (NIR, IR-A). The second wavelength range is thus longer than the first wavelength range.

[0010] The light converter comprises at least one phosphorescent luminescent material (luminophore). The luminescent material typically contains inorganic, crystalline substances with doping elements incorporated into the crystal structure as impurities. Unlike fluorescence, phosphorescence results in an afterglow that can last up to several minutes depending on the luminescent material. Conversely, a phosphorescent luminescent material also requires a certain optical charging time to raise the energy introduced by shorter-wavelength optical excitation to a higher energy level based on quantum mechanical processes.

[0011] In the field of optical smoke detection, optical smoke detectors that operate according to the two-color principle are also synonymously referred to as blue / red detectors, corresponding to the optically appearing or adjacent “blue” first wavelength range and the “red” second wavelength range.

[0012] The light emitted by the LED is emitted in a constant ratio of light from the first wavelength range (blue light component) to light from the second wavelength range (red light component). Light scattered by particles to be detected, as in the case of a scattered-light smoke detector, or light attenuated by particles to be detected, as in the case of an extinction smoke detector, exhibits a different ratio or difference depending on the type or nature of the particles.

[0013] The two-color ratio, e.g., the ratio of detected blue to detected red, is a measure of the size of the particles detected by the smoke detection unit, such as smoke particles. The smaller the detected particles, the greater the two-color ratio. Detected small particles are more likely to indicate smoke particles produced by a fire, while detected large particles are more likely to indicate dust. Instead of the blue / red ratio, the inverse, i.e., a red / blue ratio, can of course also be used. In this case, the larger the detected particles, the greater the two-color ratio, and the smaller the detected particles, the smaller the two-color ratio.

[0014] The invention is based on the finding that the AC or alternating component of the photosensor signal corresponds to the amplitude of the "blue" light component and that the DC or constant component of the photosensor signal corresponds to a component of the amplitude of the "red" light component during the respective off-times. The component A of the amplitude is determined by the ratio of the on-time of the control pulses to the luminous time constant of the phosphor. In particular, the component A follows the relationship A = 1 - e (-T ON / τ), where T ON The duty cycle of the control pulses is referred to. The component A is thus a correction factor for correctly determining the amplitude of the "red" light component.

[0015] This makes it particularly easy to calculate the two-color ratio or the two-color difference.

[0016] The blue / red ratio can be calculated, for example, from the relationship (1L - 2L / A) / (2L / A), where 1L is the first light intensity value for the additively detected "blue" and "red" light, and 2L is the second light intensity value for the detected only "red" light. Finally, A denotes the proportion according to the previously described relationship A = 1 - e (-T ON / τ).

[0017] Alternatively, instead of the two-color ratio, the two-color difference can be used to determine the type of detected particles.

[0018] The control unit is preferably a microcontroller. It is configured or programmed to electrically pulse the LED chip to emit light. By calculating the ratio or difference between the two received light intensity values ​​assigned to the "color," it is then possible to determine an equivalent particle size. This particle size can then be taken into account by the control unit when raising a fire alarm, i.e., when generating and issuing a fire alarm. For example, the control unit can be configured to issue a corresponding warning and / or alarm message by comparing the "blue" light component with the "red" light component and, if a respective minimum light intensity value is present, issue a corresponding warning and / or alarm message.

[0019] The object of the invention is further achieved with a second smoke detection unit for optical smoke detection according to the two-color principle. In this case, the second smoke detection unit has an amplifier connected downstream of the photosensor for amplifying a sensor signal detected by the photosensor, wherein the amplifier additionally comprises an offset input for applying a voltage. Furthermore, the second smoke detection unit has a control unit connected to the LED and to the amplifier. The latter is configured to control the LED by means of an electrical test pulse in the form of a "pilot tone" with a test period to emit a time-associated test light pulse. The test period consists of a test on-time and a subsequent test off-time. The test on-time is preferably in a range of 0.01 to 0.1 times the luminous time constant of the phosphor.

[0020] The control unit is further configured to determine a first light intensity value from the detected amplified sensor signal during the test duty cycle of the electrical test pulse, wherein no voltage is then applied to the offset input of the amplifier during the duty cycle.

[0021] Furthermore, the control unit is configured to subsequently apply an inverted voltage corresponding to the first light intensity value to the offset input of the amplifier and subsequently to drive the light-emitting diode by means of an electrical charging pulse to emit a time-associated charging light pulse in order to optically charge the phosphor. The electrical charging pulse has a charging duty cycle that is greater than the luminous time constant of the phosphor.

[0022] The control unit is further configured to determine a second light intensity value at the end of the charging on-time or at the beginning of the charging off-time of the electrical charging pulse from the amplified sensor signal, then to form a two-color ratio or a two-color difference from the first and second light intensity values, and finally to take the two-color ratio or the two-color difference into account when triggering the fire alarm.

[0023] By applying an inverted voltage corresponding to the test light intensity value, i.e., the opposite voltage, to the offset input, the amplifier "sees" only the red or infrared light component. The blue light component is then no longer superimposed on this red or infrared light component. Consequently, the amplification of the red or infrared light component is not subject to any limitation with regard to the amplifier's dynamic range.

[0024] In the following, the embodiments described below apply both to the previously described first smoke detection unit according to the invention and to the second smoke detection unit according to the invention.

[0025] According to one embodiment, the control unit is configured to continuously repeat the determination of the first and second light intensity values, the formation of the two-color ratio or the two-color difference, and the consideration of the two-color ratio or the two-color difference in the fire analysis, in particular in a repeating measuring cycle with a measuring cycle period in a range of 0.5 s to 100 s, preferably in a range of 0.5 s to 30 s.

[0026] According to a further embodiment, the control unit is configured to control the LED at the beginning of a repeating measurement cycle by means of an electrical test pulse with a test period duration to emit a time-associated test light pulse. Furthermore, the control unit is configured to detect a sensor signal from the photosensor and, based on the detected sensor signal, to determine a first light intensity value during the test duty cycle of the electrical test pulse. Subsequently, the control unit is configured to control the LED by means of an electrical charging pulse if the test light intensity value exceeds or has exceeded a predetermined comparison value.

[0027] The particular advantage here lies in the particularly energy-efficient operation it enables for smoke detection. The emission of the particularly short, predominantly "blue" light pulses in the first smoke detection phase offers the significant advantage that they are scattered by both small smoke particles and large particles such as dust or vapor. In contrast, the longer-lasting "red" light emitted as part of the "magenta" light in the second smoke detection phase is only slightly scattered by the small smoke particles, since the corresponding "red" light intensity value is very low, especially for short-duration test light pulses, and is therefore negligible.

[0028] This advantageously ensures complete monitoring for both smoke particles and interference. Only when a sufficient concentration of smoke particles, dust, or vapor enters the scattered light volume is the previously specified reference value exceeded. A current two-color ratio or two-color difference is then determined to determine the detected smoke type.

[0029] In particular, according to one embodiment, the charging duty cycle is in a range of 2 to 7 times, preferably in a range of 3 to 5 times, the luminous time constant of the phosphor.

[0030] According to a further embodiment, the light converter comprises the phosphorescent phosphor with a luminous time constant in a range of 5 ms to 100 ms, in particular in a range of 10 ms to 50 ms.

[0031] The object of the invention is further achieved with a scattered light smoke detector comprising a housing and a smoke detection unit according to the invention housed within the housing. The LED and the photosensor are arranged in a scattered light array and aligned toward a common scattered light center. The housing has smoke inlet openings for the passage of ambient air into the interior of the housing, wherein the housing is shielded against the penetration of direct ambient light into the interior of the housing.

[0032] The object of the invention is further achieved with an extinction smoke detector comprising a housing and a smoke detection unit according to the invention accommodated in the housing. The LED and the photosensor are arranged such that the photosensor detects direct light from the LED. The housing has smoke inlet openings for the passage of ambient air into the interior of the housing, wherein the housing is shielded against the penetration of direct ambient light into the interior of the housing.

[0033] Finally, the object of the invention is achieved with an open scattered light smoke detector comprising a housing and a smoke detection unit according to the invention mounted on the housing. The LED and the photosensor are arranged in or on the housing and are optically aligned to a common scattered light center, with the scattered light center located outside the scattered light smoke detector.

[0034] The invention and advantageous embodiments of the present invention are explained using the following figures as examples. They show: Fig. 1 shows an example of the course of an electrical test pulse with a following electrical charging pulse, Fig. 2 shows an example of the course of an electrical test pulse with a subsequent charging pulse and the course of the total light intensity with offset, Fig. 3 an example of a smoke detection unit according to the invention for optical scattered light detection with a light-emitting diode with phosphorescent phosphor and a downstream photosensor, Fig. 4 shows an example of a smoke detection unit according to the invention for optical scattered light detection with a light-emitting diode with phosphorescent phosphor, an amplifier and a photosensor, and Fig. 5 an example of a smoke detection unit according to the invention for transmitted light measurement along a measuring section with a light-emitting diode with phosphorescent phosphor and a photosensor.

[0035] Fig. To facilitate understanding of the invention, Figure 3 first shows an example of a smoke detection unit 10 for optical scattered light detection. The smoke detection unit 10 according to the invention comprises a light-emitting diode 1 with a phosphorescent phosphor and a downstream photosensor 2. The light-emitting diode 1 and the photosensor 2 are arranged in a so-called scattered light arrangement.

[0036] In the scattered light arrangement shown, the photosensor 2 is arranged at a scattered light angle α of 60° to the light-emitting diode 1 for scattered light detection. EA denotes the optical detection range of the photosensor 2. The light-emitting diode 1 has a (single) "monochrome" LED chip 3 that emits a "blue" light beam in a first wavelength range from 315 nm to 490 nm. The LED chip 3 is arranged on a chip carrier of the light-emitting diode 1. A light converter 4 is applied to the LED chip 3, which converts part of the light emitted by the LED chip 3 into light of a second wavelength range in a range from 640 nm to 1400 nm, i.e., into red to infrared light. MAG denotes a "magenta" light beam, which is intended to illustrate the optically additive superposition of blue and red light.The term "magenta" is to be understood only symbolically here and is not applicable to optically invisible near ultraviolet (NUV) and near infrared (NIR) light. SA denotes the geometric main axis or axis of symmetry of the light-emitting diode 1, which coincides with the optical transmission axis of the light-emitting diode 1. Preferably, the LED chip 3 is arranged orthogonally to the geometric main axis SA. The light-emitting diode 1 further comprises a transparent LED housing 5, preferably made of plastic or glass, in which the connection contacts and the chip carrier are arranged.

[0037] The control unit 6 shown is preferably a microcontroller. As in the present example, it may already have an integrated A / D converter 7 for detecting a photosensor signal PS from the photosensor 2. It also has an output for pulsed control of the LED 1 using electrical control pulses EAI, ETI, as well as an output for outputting a fire alarm AL in the event of a fire being detected. PRG denotes a computer program that is loaded into the microcontroller 6 and executed by it to implement the optical smoke detection according to the invention. For this purpose, the computer program PRG has suitable program steps. Together with the computer program PRG, the microcontroller 6 is then configured or programmed to implement the optical smoke detection according to the invention in accordance with independent patent claims 1 and 2.

[0038] Fig. Figure 1 shows, as an example, the curve of an electrical test pulse ETI with a subsequent electrical charging pulse EAI as well as the curve VG of the total light intensity I. The dotted line shows the curve of two short-term test light pulses TLI emitted by the LED, which, compared to the rectangular signal shape of the electrical test control pulses ETI, are only slightly distorted by the optically inert effect of the light converter. With T TON is test duty cycle and with T TOFF a test off time, which together represent the T T Test period duration.

[0039] Z denotes the switching state of an electrically controlled light-emitting diode 1, where ON corresponds to a lit state of the light-emitting diode 1 and OFF corresponds to a non-lit state of the light-emitting diode 1.

[0040] In the left part of the Fig. 1 it can be seen that during the test duty cycle T TON The first detected light intensity value 1L does not exceed a reference value VL. In this case, the scattered light received by the particles to be detected is too low to assess whether a possible fire or disturbance is present. After a cyclically repeating measurement cycle period TP, e.g., after 30 seconds, it is evident that the first detected light intensity value 1L in the received test light pulse TP exceeds the reference value VL. A charging light pulse ALI is emitted for the subsequent evaluation according to the two-color principle.

[0041] In the lower part of the Fig. Figure 1 shows the corresponding curve VG of the total light intensity I. The light intensity I is detected by a photosensor or photodiode and output as a photosensor signal. The photosensor signal is typically a current signal whose amplitude is proportional to the detected light intensity I. It can be seen that the light intensity I of the received test light pulses TP roughly follows the pulsed signal shape of the emitted test light pulses TLI.

[0042] It can also be seen that the charging duty cycle T AON many times larger than the optical luminosity time constant τ. With T A is the charging period and T AOFF Due to the comparatively long optical charging, in this case the following charging-off time T AOFFThe electrical charging pulse EAI provides a second light intensity value 2L with a high signal level that corresponds to the received red or infrared value. This advantageously enables particularly precise measurement of the second light intensity value 2L.

[0043] Here, with the start of a received charging light pulse AP, the light intensity I increases abruptly and almost instantaneously by a difference value B, which corresponds to the scattered light component of the first wavelength range, i.e., the "blue" and optically undelayed light component. With the respective abrupt end of the received charging light pulse AP, the light intensity I also decreases abruptly and almost instantaneously by the difference value B. This abrupt progression in the progression VG of the total light intensity I bears the reference symbol VB.

[0044] Superimposed on this "blue" curve VB of the light intensity I, the scattered light component of the second wavelength range, i.e., the "red" and optically delayed light component, increases only slowly with the start of a received charging light pulse AP. This delayed curve in the curve VG of the total light intensity I bears the reference symbol VR.

[0045] In the lower part of the Fig. 1 also shows the corresponding graphically continued course VOL of the optical luminous time constant τ. Here, the charging time T AON and the corresponding illumination duration of the respective received charging light pulse AP is significantly greater than the optical illumination time constant τ. If the received charging light pulse AP were to be continuously applied - as shown in dashed lines - the light intensity of the "red" light component would satisfy the relationship 1 - e (-T ON / τ) and, after a certain luminous time constant τ, correspond to the saturation value R for the "red" light component. With the respective abrupt end of the received charging light pulse AP, the light intensity I of the "red" light component also gradually decreases.

[0046] Reference symbol 1L denotes a first light intensity value, which is recorded during an electrical test pulse ETI. Reference symbol 2L denotes a second light intensity value, which is recorded during an electrical charging pulse EAI. T ADCThis refers to a sampling period of an analog / digital converter. The first and second light intensity values ​​1L, 2L, respectively, recorded by the analog / digital converter, are subsequently further processed by an electronic control unit to generate a two-color ratio or a two-color difference from the first and second light intensity values ​​1L, 2L, and to take this ratio or difference into account when triggering the fire alarm.

[0047] Fig. 2 shows, as an example, the course of an electrical test pulse ETI with the following electrical charging pulse EAI as well as the course VG of the total light intensity I with offset.

[0048] In the left part of the Fig. 2, the light-emitting diode is first triggered by an electrical test pulse ETI to emit a time-associated test light pulse TLI and during the duty cycle T TONof the electrical test pulse ETI, a first light intensity value 1L is recorded and determined. The first light intensity value 1L corresponds almost to the blue light component B in the received test light pulse TP, since the red light component R is much shorter than the light converter's operating time T TON of the electrical test pulse ETI could not yet contribute a significant signal. For offset compensation, an inverted voltage corresponding to the first light intensity value 1L is subsequently applied to an offset input of an amplifier. This is shown by the dashed constant curve VB- of the first light intensity value with an inverted first light intensity value B-. This creates the curve VG of the total light intensity I in the image of the Fig. 2 is shifted downward. Due to the signal-technical subtraction of the blue component B from the overall signal waveform VG, only the offset-compensated waveform VR- of the light intensity I of the second wavelength range remains. The blue light component B is then no longer superimposed on this red or infrared light component R. Consequently, the amplification of the red or infrared light component R is no longer subject to any limitation with regard to the dynamic range of the amplifier.

[0049] Fig. 4 shows an example of a smoke detection unit 10 according to the invention for optical scattered light detection with a light-emitting diode 1 with phosphorescent phosphor, an amplifier 8 and a photosensor 2.

[0050] Compared to the previous Fig. 3, an amplifier 8 is provided for offset compensation, ie for compensating the «blue» light component in the photosensor signal PS of the photosensor 2. In the example of Fig. 3 and Fig. 4, the photosensor 2 is a photodiode. For this purpose, the photosensor signal PS is fed to a non-inverting input (+) of an amplifier 8 designed as an operational amplifier. At the same time, the output of the operational amplifier 8 is fed back to the non-inverting input (+) via a feedback circuit (not further described) - symbolized by an ohmic resistor. The present circuit arrangement also schematically represents a known transimpedance converter, which converts the photocurrent generated by the photodiode 2 into a proportional photovoltage at the output of the operational amplifier 8. The offset compensation is realized here by a previously detected first light intensity value 1L during the duty cycle T TONan electrical test pulse ETI is detected by an analog / digital converter 7 of the microcontroller 6, and a voltage corresponding to the first light intensity value 1L is output by a digital / analog converter 9 of the microcontroller 6 and supplied to a voltage-controlled current source. This voltage-controlled current source is then connected to an inverting input (-) of the operational amplifier 8 for offset compensation.

[0051] Fig. 5 finally shows an example of a smoke detection unit 10 according to the invention for transmitted light measurement along a measuring section MESS with a light-emitting diode 1 with phosphorescent phosphor and a photosensor 2. The control unit 6 is configured to output a fire alarm AL if necessary depending on the two-color ratio and thus on the smoke type determined.

[0052] The invention relates to a smoke detection unit 10 for optical smoke detection according to the two-color principle, which comprises a light-emitting diode 1 for light emission in a first and second wavelength range, having an LED chip 3 and a light converter 4 with a phosphorescent luminescent material with a lighting time constant τ. The smoke detection unit 10 comprises a photosensor 2 and a control unit 6, which is designed to test the light-emitting diode 1 by means of an electrical test pulse ETI with a test duty cycle T TON preferably in a range of 0.02 to 0.2 times the luminous time constant τ of the phosphor, to determine a first light intensity value 1L from a detected photosensor signal PS during the test duty cycle T TONto determine, further subsequently to control the light-emitting diode 1 by means of a temporally longer electrical charging pulse EAI in order to optically charge the phosphor, a second light intensity value 2L at the end of the charging duty cycle T AON or at the beginning of the charging off time T AOFF to determine from the photosensor signal PS, to form a two-color ratio or a two-color difference from the first and second light intensity values ​​1L, 2L, and to take this or these into account in the fire alarm AL. List of reference symbols 1 (two-color) light-emitting diode, LED 2 Photosensor, semiconductor photodiode 3 LED chip, blue LED chip, UV LED chip 4 light converter, light conversion layer 5 housings, plastic housings, LED housings 6 Control unit, microcontroller 7 analog / digital converters, ADC 8 amplifiers 9 digital / analog converters, DAC α scattered light angle τ luminous time constant 2τ ... 3τ luminous time constants 1L first light intensity value 2L second light intensity value AL Alarm, alarm information ALI emitted charging light pulse AP received charging light pulse B Difference value, proportion of the first light intensity B- inverted first light intensity value EA receiving axis, optical axis EAI electrical charging pulse ETI electrical test pulse I Light intensity MEASURING measuring section ON switched on state OFF switched off state PRG computer program, computer program product PS sensor signal, photosensor signal R Final value of the second light intensity SA transmission axis, symmetry axis of the LED SZ Scattered Light Center t time, timeline TA Recharge period duration T AON Charging time T AOFF Charging-off time T T Test period duration T TON Test duty cycle T TOFF Test off time T ABC Sampling time TLI emitted test light pulse TP received test light pulse, received short-term light pulse TZ measurement cycle period VB Course of the light intensity of the first wavelength range VB- inverted constant curve of the test light intensity value VG Course of the total light intensity VL comparison value VOL Course of the optical charging time constant VR course of the light intensity of the second wavelength range VR' offset-compensated light intensity curve of the second wavelength range Z switching state QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 3 574 530 B1

[0003] EP 3 276 680 A1

[0003]

Claims

[1] Smoke detection unit for optical smoke detection according to the two-color principle, which has - a light-emitting diode (1) with an LED chip (3) for emitting light in a first wavelength range and with a light converter (4) for converting a portion of the emitted light into light of a second wavelength range, wherein the light converter (4) comprises a phosphorescent luminescent material with a luminous time constant (τ), - a photosensor (2) spectrally tuned to the light emitted by the light-emitting diode (1), and - a control unit (6) connected to the light-emitting diode (1) and to the photosensor (2), which is designed to - the light-emitting diode (1) by means of an electrical test pulse (ETI) with a test period (T T ) to emit a time-associated test light pulse (TLI), whereby the test period (T T ) consists of a test duty cycle (T TON) and a subsequent test off time (T TOFF ), where the test duty cycle (T TON ) is preferably in a range of 0.02 to 0.2 times the luminous time constant (τ) of the phosphor, - from a detected sensor signal (PS) of the photosensor (2) a first light intensity value (1L) during the test duty cycle (T TON ) of the electrical test impulse (ETI), - subsequently controlling the light-emitting diode (1) by means of an electrical charging pulse (EAI) to emit a time-associated charging light pulse (ALI) in order to optically charge the phosphor, wherein the electrical charging pulse (EAI) has a charging duty cycle (T AON ) which is greater than the luminous time constant (τ) of the phosphor, - a second light intensity value (2L) at the end of the charging time (T AON ) or at the beginning of the charging off time (T AOFF) of the electrical charging pulse (EAI) from the sensor signal (PS), - to form a two-colour ratio or a two-colour difference from the first light intensity value (1L) and the second light intensity value (2L), and - to take into account the two-colour ratio or the two-colour difference in the fire alarm (AL). [2] Smoke detection unit for optical smoke detection according to the two-color principle, which has - a light-emitting diode (1) with an LED chip (3) for emitting light in a first wavelength range and with a light converter (4) for converting a portion of the emitted light into light of a second wavelength range, wherein the light converter (4) comprises a phosphorescent luminescent material with a luminous time constant (τ), - a photosensor (2) spectrally tuned to the light emitted by the light-emitting diode (1), - an amplifier (8) connected downstream of the photosensor (2) for amplifying a sensor signal (PS) detected by the photosensor (2), the amplifier (8) additionally having an offset input for applying a voltage, and - a control unit (6) connected to the light-emitting diode (1) and to the amplifier (8), which is designed to - the light-emitting diode (1) by means of an electrical test pulse (ETI) with a test period (T T ) to emit a time-associated test light pulse (TLI), whereby the test period (T T ) consists of a test duty cycle (T TON ) and a subsequent test off time (T TOFF ), where the test duty cycle (T TON ) is preferably in a range of 0.02 to 0.2 times the luminous time constant (τ) of the phosphor, - from the recorded amplified sensor signal (PS) a first light intensity value (1L) during the test duty cycle (T TON ) of the electrical test impulse (ETI), whereby during the test duty cycle (T TON ) no voltage is applied to the offset input of the amplifier, - subsequently applying an inverted voltage corresponding to the first light intensity value (1L) to the offset input of the amplifier (8), - subsequently controlling the light-emitting diode (1) by means of an electrical charging pulse (EAI) to emit a time-associated charging light pulse (ALI) in order to optically charge the phosphor, wherein the electrical charging pulse (EAI) has a charging duty cycle (T AON ) which is greater than the luminous time constant (τ) of the phosphor, - a second light intensity value (2L) at the end of the charging time (T AON ) or at the beginning of the charging off time (T AOFF) of the electrical charging pulse (EAI) from the amplified sensor signal (PS), - to form a two-colour ratio or a two-colour difference from the first light intensity value (1L) and the second light intensity value (2L), and - to take into account the two-colour ratio or the two-colour difference in the fire alarm (AL). [3] Smoke detection unit according to claim 1 or 2, wherein the control unit (6) is configured to continuously repeat the determination of the first light intensity value (1L) and the second light intensity value (2L), the formation of the two-color ratio or the two-color difference and the consideration of the two-color ratio or the two-color difference in the fire analysis, in particular in a repeating measuring cycle with a measuring cycle period (TZ) in a range of 0.5 s to 100 s, preferably in a range of 0.5 s to 30 s. [4] Smoke detection unit according to one of the preceding claims, wherein the control unit (6) is arranged to - to control the light-emitting diode (1) at the beginning of a repeating measuring cycle by means of an electrical test pulse (ETI) to emit a time-associated test light pulse (TLI), - based on the detected sensor signal (PS), a first light intensity value (1L) during the duty cycle (T TON ) of the electrical test impulse (ETI), and - subsequently controlling the light-emitting diode (1) by means of an electrical charging pulse (EAI) if the first light intensity value (1L) has exceeded a predetermined comparison value (VL). [5] Smoke detection unit according to one of the preceding claims, wherein the charging duty cycle (T AON ) is in a range of 2 to 7 times, preferably in a range of 3 to 5 times, the luminous time constant (τ) of the phosphor. [6] Smoke detection unit according to one of the preceding claims, wherein the light converter (4) comprises the phosphorescent phosphor with a luminous time constant (τ) in a range of 5 ms to 100 ms, in particular in a range of 10 ms to 50 ms. [7] Scattered light smoke detector, with a housing and with a smoke detection unit (10) accommodated in the housing according to one of claims 1 to 6, wherein the light-emitting diode (1) and the photosensor (2) are arranged in a scattered light arrangement and are aligned with a common scattered light center (SZ), wherein the housing has smoke inlet openings for the passage of ambient air into the interior of the housing and wherein the housing is shielded against the penetration of direct ambient light into the interior of the housing. [8] Extinction smoke detector, with a housing and with a smoke detection unit (10) accommodated in the housing according to one of claims 1 to 6, wherein the light-emitting diode (1) and the photosensor (2) are arranged such that the photosensor (2) detects direct light from the light-emitting diode (1), wherein the housing has smoke inlet openings for the passage of ambient air into the interior of the housing and wherein the housing is shielded against the penetration of direct ambient light into the interior of the housing. [9] Open scattered light smoke detector, with a housing and with a smoke detection unit (10) accommodated on the housing according to one of claims 1 to 6, wherein the light-emitting diode (1) and the photosensor (2) are arranged in or on the housing and are optically aligned to a common scattered light center (SZ), wherein the scattered light center (SZ) is located outside the open scattered light smoke detector in the open air.

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