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Smoke detection by way of two spectrally different scattered light measurements

A technology of scattered light and smoke, applied to fire alarms, instruments, alarms, etc., can solve the problem of high cost of fire alarm equipment

Inactive Publication Date: 2011-01-19
SIEMENS SWITZERLAND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But the shortcoming that this fire alarm has is that it has a plurality of mutually independent optical paths respectively having both the optical transmitter and the optical receiver.
Therefore, the equipment cost of the fire alarm is relatively high

Method used

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  • Smoke detection by way of two spectrally different scattered light measurements
  • Smoke detection by way of two spectrally different scattered light measurements
  • Smoke detection by way of two spectrally different scattered light measurements

Examples

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Comparison scheme
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Embodiment Construction

[0059] figure 1 The scattered light smoke alarm 100 is shown in plan view. The scattered light smoke alarm 100 has figure 1 A circuit board not shown in the figure, on which all electronic components and photoelectric components of the scattered light smoke alarm 100 are installed.

[0060] The scattered-light smoke alarm 100 has a light-transmitting device 110 comprising two light sources, namely a first light-emitting diode 111 and a second light-emitting diode 112 . The first light emitting diode 111 has a light emitting chip 111a. According to the exemplary embodiment shown here, the chip 111a emits infrared light with a wavelength of 880 nm. The second light emitting diode 112 has a light emitting chip 112a. According to the embodiment shown here, chip 112a emits blue light with a wavelength of 420 nm.

[0061] Both light-emitting diodes 111 and 112 are operated in pulsed mode, wherein each light-emitting diode 111 , 112 emits a light pulse with a duration of, for ex...

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PUM

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Abstract

A device and a method for detecting smoke based on the principle of optical scattered light measurements are described. The device (100) described comprises a light emitting device (110), configured to issue a temporal succession of light pulses, wherein a first light pulse comprises a first spectral distribution and a second light pulse comprises a second spectral distribution different from the first spectral distribution. The device (100) further comprises a light receiver (120), configured to receive a first scattered light from the first light pulse and a second scattered light from the second light pulse, and configured to prepare a first output signal that is indicative for the first scattered light, and a second output signals that is indicative for the second scattered light. Also, the device (100) described comprises an evaluation unit that is configured to compare the first output signal with the second output signal. Preferably, the light emitting device (110) and the light receiver (120) are arranged directly adjacent to one another.

Description

technical field [0001] The invention relates to the technical field of danger alarm technology. In particular, the invention relates to a device for detecting smoke based on optical scattered light measurements. Furthermore, the invention relates to a method for detecting smoke based on the principle of optical scattered light measurement. Background technique [0002] Optical or photoelectric smoke alarms usually work according to the scattered light method. What is used here is that clean air reflects practically no light. However, if smoke particles are present in the air, the illumination light emitted by the light source is at least partially scattered at the smoke particles. That way, a portion of this scattered light falls on light receivers that are not directly illuminated by the beam. In the absence of smoke particles in the air, the illuminating light cannot reach the photosensitive sensor. [0003] A fire alarm with a laser light source is known from EP 0 47...

Claims

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Application Information

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IPC IPC(8): G08B17/107
CPCG08B17/107G08B29/043G08B17/113
Inventor K·米勒M·罗普费G·A·滕基奥W·福伦魏德
Owner SIEMENS SWITZERLAND
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