Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B1/00—Systems for signalling characterised solely by the form of transmission of the signal
  • G08B1/08—Systems for signalling characterised solely by the form of transmission of the signal using electric transmission ; transformation of alarm signals to electrical signals from a different medium, e.g. transmission of an electric alarm signal upon detection of an audible alarm signal
• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B3/00—Audible signalling systems; Audible personal calling systems
  • G08B3/10—Audible signalling systems; Audible personal calling systems using electric transmission; using electromagnetic transmission

Definitions

• the object of the invention is to achieve this object.
• this object is solved with an alarm with a sound signal.
• An alarm with a sound signal may seem improbable for persons with impaired hearing, but since the majority of persons with impaired hearing has the reduction in the high or middle area low tones can be used that are audible for the majority of those with impaired hearing.
• a square wave shape for instance a frequency of 100, one on 200, one on 300 and one on 500Hz may be mixed. Since it is a square wave and in the frequency area up to 500Hz it is possible to use a sufficiently powerful sound in order to make the sound audible also to persons with impaired hearing in this frequency area, at the same time as it is possible to stay below the pain threshold level for persons with ordinary hearing.
• a square wave shape for instance a frequency of 100, one on 200, one on 300 and one on 500Hz may be mixed. Since it is a square wave and in the frequency area up to 500Hz it is possible to use a sufficiently powerful sound in order to make the sound audible also to persons with impaired hearing in this frequency area, at the same time as it is possible to stay below the pain threshold level for persons with ordinary hearing.
• the loudspeaker with square wave shaped pulses also add one or several signals with sawtooth shape and a low frequency, for instance coinciding with those of the square wave, a corresponding additional sound is obtained in the low frequency area facilitating the hearing
• the alarm shown in fig 1 includes a battery unit 1 , an electronic sound circuit with an amplifier 2, a smoke detector and a flashlight 4.
• the amplifier 2 is connected to a loudspeaker 5 to which is added a resonator 6 comprising a cylindric tube with a diameter corresponding to the outlet opening of the loudspeaker and extending axially out from the loudspeaker.
• the resonator tube provides together with the depth of the loudspeaker a suitable resonance length for one of the desired frequencies.
• a loudspeaker grid 7 is arranged in front of the opening of the resonator tube in the end opposed to that of the loudspeaker end arranged.
• the fire alarm shown in the drawings function in such a manner that at a possible fire the smoke detector 3, that preferably is of ionization type, in order to ascertain a long time of use, detect the smoke.
• the smoke detector 3 activates the flashlight and the sound circuit with its loudspeaker.
• the amplifier feeds the loudspeaker with a signal in accordance with the invention.
• the signal consist of square waves mixed with sawtooth waves and a wobbling hard sound.
• the square wave in itself sound approximately as a net frequency buzz from a poorly fastened apparatus but with a higher frequency, while the saw tooth wave gives more normal tone.
• the resonator By the use of the resonator a considerable gain is obtained for the sounds or tones that are of interest from a hearing point of view for persons with impaired hearing. This increase is apparent from the enclosed table that has been measured for an alarm sound in accordance with the invention. As is apparent from the table the straight cylindrical shown resonator tube can be exchanged for an outward from the loudspeaker slightly conically converging tube, at which a certain additional gain is obtained for the interesting frequencies. Recalculated to a maximum power of 10W fed to the loudspeaker element this means that the sound pressure levels i the 50Hz-octave at a distance of lm would be in the size order 95dB.
• the conical resonator gives somewhat higher sound pressure levels than the straight in the 500Hz band and somewhat lower in the 1000-2000Hz band. From the point of hearing the 500Hz band is the most important, which is apparent from a comparison of the sound providers sound levels in relation to the threshold values in the column most to the right. As is apparent the measured sound levels at 500Hz mean 75 - 79dB over the normal hearing threshold while at 250Hz the above values are 49 - 61dB over a normal hearing threshold. At a free propagation of the sound the sound level is reduced with 6dB at every doubling of the distance. Indoors the sound level is less reduced due to reflexes in floor, roof etc. The maximum sound level at ca.
• 10m distance with a nominal power feed of 10W will be at least 75-80dB SPL in the 500Hz-band.
• the signal can be appreciated to be well audible for persons with impaired hearing of 50dB at 500Hz.
• the signal can be registered by the majority of all persons with impaired hearing, since the dominating types of hearing damages means comparatively well preserved hearing thresholds in the low frequency area.
• the electric signals that is in particular the electric square pulses and sawtooth pulses that are made and mixed in the sound circuit and amplified with the connected amplifier and resonator may either be stored digitally as a recorded and tested sound sequence, that is then played over and over again at activation or as mathematical functions for the voltage pulses or current signals that the loudspeaker is fed with.
• the sawtooth shape as well as the square shape are symmetric.
• the alarm can be activated and heard for a long time when sounding and with a high sound level even with a moderate battery size.
• the above described device is intended to be arranged as an individual fire alarm, for instance at the home of a person with reduced hearing.
• the used sound frequencies can be varied in different ways and be tested to obtain the best possible hearability for persons with impaired hearing.
• a person with impaired hearing may have his own alarm signal developed if he has difficulties to hear the normal alarm signal for persons with impaired hearing.
• the alarm signal should be comparatively normalized so that a person with impaired hearing may realize that it is a fire alarm or other alarm he is hearing independent of if he is at home, at a hospital etc.
• the invention provide in relation to the known and used alarms improved safety for the majority, and a cost per alarm device that is only a fraction of the cost for a vibrator alarm device.
• the sound pressure level is given in dB re. 20 ⁇ Pa for an electric signal voltage to the loudspeaker of IN RMS.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Fire Alarms (AREA)
• Alarm Systems (AREA)
• Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
• Lubrication Of Internal Combustion Engines (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20414738

Family Applications (1)

Country Status (8)

Cited By (1)

Citations (1)

• 1999
  • 1999-03-05 SE SE9900801A patent/SE9900801L/ unknown
• 2000
  • 2000-03-02 AU AU33410/00A patent/AU3341000A/en not_active Abandoned
  • 2000-03-02 DE DE60006796T patent/DE60006796T2/de not_active Expired - Lifetime
  • 2000-03-02 AT AT00911546T patent/ATE255259T1/de not_active IP Right Cessation
  • 2000-03-02 JP JP2000604384A patent/JP2002539540A/ja not_active Withdrawn
  • 2000-03-02 ES ES00911546T patent/ES2211514T3/es not_active Expired - Lifetime
  • 2000-03-02 WO PCT/SE2000/000410 patent/WO2000054235A1/en active IP Right Grant
  • 2000-03-02 EP EP00911546A patent/EP1169689B1/en not_active Expired - Lifetime

Patent Citations (1)

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