Reversing alarm

Abstract

A reversing alarm for a vehicle emits an audible signal in the form of pulses of broad band sound when the vehicle is put into reverse gear. The broad band sound allows persons in the vicinity to locate the vehicle, as the human brain is able to process broad band sound to pinpoint the location of the sound source in a way which is not possible with single tone sounds. The alarm is implemented via a simple electronic circuit which uses a zener diode as a signal generator 20 to generate the broad band sound.

What is claimed is: 
     
       1. A reversing alarm for a vehicle, said reversing alarm comprising:
 a signal generating device, 
 said signal generating device including a zener diode as a broad-band signal generating component thereof to generate only a broad band sound signal, and a speaker connected only to said broad band sound signal from which only broad band sound is emitted. 
 
     
     
       2. A reversing alarm according to  claim 1 , in which the alarm further comprises bandwidth narrowing means for narrowing the bandwidth of the broad band sound signal before emission of the audible signal. 
     
     
       3. A reversing alarm for a vehicle according to  claim 2  in which the bandwidth narrowing means comprises a band-pass filter. 
     
     
       4. A reversing alarm for a vehicle according to  claim 1 , in which the audible broad band sound signal is emitted in pulsed bursts. 
     
     
       5. A reversing alarm for a vehicle according to  claim 4 , comprising a muting circuit, driven by an intermittent signal generator, which acts to alternately block and pass the broad band sound signal to produce pulsed bursts of sound. 
     
     
       6. A reversing alarm for a vehicle according to  claim 5 , further comprising a clipper circuit which compresses and reshapes the corners of the pulsed signal. 
     
     
       7. A reversing alarm for a vehicle according to  claim 4 , in which the pulsed bursts of sound have a repetition frequency of substantially 1.5 Hz (90 pulses per minute). 
     
     
       8. A reversing alarm for a vehicle according to  claim 1 , which is powered by a standard 12 V DC or 24 V DC vehicle battery. 
     
     
       9. A reversing alarm for a vehicle according to  claim 8 , comprising a voltage regulator which acts to regulate the voltage from the battery before the voltage is applied to power the reversing alarm. 
     
     
       10. A reversing alarm for a vehicle according to  claim 9 , in which the voltage regulator produces a voltage of substantially 8 V DC. 
     
     
       11. A reversing alarm for a vehicle according to  claim 1 , and comprising a speaker from which the broad band sound is emitted. 
     
     
       12. A reversing alarm for a vehicle according to claim  11  1, in which the speaker is waterproof. 
     
     
       13. A reversing alarm for a vehicle according to  claim 1 , in which the components of the alarm are mounted within a housing adapted for mounting on the exterior of a vehicle. 
     
     
       14. A reversing alarm for a vehicle according to  claim 1 , and further comprising a light source which provides a visible alarm when the alarm is in use. 
     
     
       15. A reversing alarm for a vehicle according to  claim 1 , which, when fitted to a vehicle, is automatically activated when the vehicle is put into reverse. 
     
     
       16. A method for producing an audible signal from a reversing alarm for a vehicle, said method comprising the steps of:
 generating a broad band sound signal comprising a sound signal of substantially uniform intensity over an audible frequency range that can be processed by a human to locate the source of the signal and excludes pure tonal sound signals and other sound signals that materially affect the dissipation or reduction in noise nuisance of the sound signal of substantially uniform intensity,   narrowing the bandwidth of the broad band sound signal before emission of the audible signal from the reversing alarm,   intermittently driving a muting circuit with an intermittent signal generator to alternately block and pass the broad band sound signal to produce pulsed bursts of sound, and   compressing and reshaping the corners of the pulsed bursts of sound with a clipper circuit, and   emitting only the compressed and reshaped broad band sound signal in pulsed bursts as said audible signal.    
     
     
       17. The method for producing an audible signal from a reversing alarm for a vehicle according to claim 16, said method further comprising the step of:
 using a band-pass filter to narrow the bandwidth of the broad band sound signal before emission of the audible signal from the reversing alarm.    
     
     
       18. The method for producing an audible signal from a reversing alarm for a vehicle according to claim 16, said method further comprising the step of:
 repeating the pulsed bursts of sound at a frequency of substantially 1.5 Hz (90 pulses per minute).    
     
     
       19. The method for producing an audible signal from a reversing alarm for a vehicle according to claim 16, said method further comprising the step of:
 using a zener diode as the signal generating device to generate the broad band sound signal.    
     
     
       20. The method for producing an audible signal from a reversing alarm for a vehicle according to claim 16, said method further comprising the step of:
 supplying power to the reversing alarm from a standard 12 V DC or 24 V DC battery.    
     
     
       21. The method for producing an audible signal from a reversing alarm for a vehicle according to claim 20, said method further comprising the step of:
 regulating the voltage supplied from the battery to the reversing alarm to a voltage of about 8 V DC.    
     
     
       22. The method for producing an audible signal from a reversing alarm for a vehicle according to claim 16, said method further comprising the step of:
 emitting the broad band sound signal from a speaker.    
     
     
       23. The method for producing an audible signal from a reversing alarm for a vehicle according to claim 16, said method further comprising the step of:
 activating a light source to provide a visible alarm when the alarm is in use.    
     
     
       24. The method for producing an audible signal from a reversing alarm for a vehicle according to claim 16, said method further comprising the step of:
 automatically activating the light source to provide a visible alarm when the vehicle is put into reverse.    
     
     
       25. A reversing alarm for a vehicle which in use produces an audible signal, said reversing alarm comprising:
 a signal generating device to generate a broad band sound signal comprising a sound signal of substantially uniform intensity over an audible frequency range that can be processed by a human to locate the source of the signal and excludes pure tonal sound signals and other sound signals that materially affect the dissipation or reduction in noise nuisance of the sound signal of substantially uniform intensity,   bandwidth narrowing means for narrowing the bandwidth of the broad band sound signal before emission of the audible signal, in which the audible signal is emitted in pulsed bursts,   a muting circuit, the muting circuit intermittently driven by an intermittent signal generator, which acts to alternately block and pass the broad band sound signal to produce a pulsed signal,   a clipper circuit which compresses and reshapes the corners of the pulsed signal, and   a speaker for attachment to said vehicle and connected to said clipper circuit that produces only said audible signal.    
     
     
       26. The reversing alarm for a vehicle according to claim 25 wherein the bandwidth narrowing means comprises a band-pass filter.  
     
     
       27. The reversing alarm for a vehicle according to claim 25 wherein the pulsed bursts of sound have a repetition frequency of substantially 1.5 Hz (90 pulses per minute).  
     
     
       28. The reversing alarm for a vehicle according to claim 25 wherein the signal generating device comprises a zener diode.  
     
     
       29. The reversing alarm for a vehicle according to claim 25 wherein the reversing alarm is powered by a standard 12 V DC or 24 V DC vehicle battery.  
     
     
       30. The reversing alarm for a vehicle according to claim 29 further comprising a voltage regulator which acts to regulate the voltage from the battery before the voltage is applied to power the reversing alarm.  
     
     
       31. The reversing alarm for a vehicle according to claim 30 wherein the voltage regulator produces a voltage of substantially 8 V DC.  
     
     
       32. The reversing alarm for a vehicle according to claim 25 wherein the speaker is waterproof.  
     
     
       33. The reversing alarm for a vehicle according to claim 25 wherein the components of the reversing alarm are mounted in a housing adapted for mounting on the exterior of a vehicle.  
     
     
       34. The reversing alarm for a vehicle according to claim 25 further comprising a light source which provides a visible signal when the reversing alarm is in use.  
     
     
       35. The reversing alarm for a vehicle according to claim 25 wherein when the reversing alarm is fitted to a vehicle, and the reversing alarm is automatically activated when the vehicle is put into reverse.  
     
     
       36. A reversing alarm for a vehicle which in use produces an audible signal, said reversing alarm comprising:
 a signal generating device to generate a broad band sound signal comprising a sound of substantially uniform intensity over an audible frequency range that can be processed by a human to locate the source of the signal and excludes pure tonal sound signals and other sound signals that materially affect the dissipation or reduction in noise nuisance of the sound signal of substantially uniform intensity, and   circuitry for processing and emitting only the broad band sound signal as said audible signal.    
     
     
       37. The reversing alarm for a vehicle according to claim 36 wherein the audible threshold of the emitted audible broad band sound signal is about 5 db less than a pure-tone reversing alarm.  
     
     
       38. The reversing alarm for a vehicle according to claim 36 wherein the circuitry for processing the broad band sound signal includes bandwidth narrowing means for narrowing the bandwidth of the broad band sound signal before emission of the audible signal.  
     
     
       39. The reversing alarm for a vehicle according to claim 38 wherein the bandwidth narrowing means comprises a band-pass filter.  
     
     
       40. The reversing alarm for a vehicle according to claim 36 wherein the circuitry for processing the broad band sound signal includes a circuit which acts to alternately block and pass the broad band sound signal to produce pulsed bursts of sound.  
     
     
       41. The reversing alarm for a vehicle according to claim 36 wherein the circuitry for processing the broad band sound signal includes a clipper circuit which compresses and reshapes the corners of the pulsed signal.  
     
     
       42. The reversing alarm for a vehicle according to claim 40 wherein the pulsed bursts of sound have a repetition frequency of substantially 1.5 Hz (90 pulses per minute).  
     
     
       43. The reversing alarm for a vehicle according to claim 36 wherein the signal generating device comprises a zener diode.  
     
     
       44. The reversing alarm for a vehicle according to claim 36 wherein the reversing alarm is powered by a standard 12 V DC or 24 V DC vehicle battery.  
     
     
       45. The reversing alarm for a vehicle according to claim 36 further comprising a speaker from which the broad band sound is emitted.  
     
     
       46. The reversing alarm for a vehicle according to claim 36 wherein the components of the reversing alarm are mounted in a housing adapted for mounting on the exterior of a vehicle.  
     
     
       47. The reversing alarm for a vehicle according to claim 36 wherein when the reversing alarm is fitted to a vehicle, and the reversing alarm is automatically activated when the vehicle is put into reverse.  
     
     
       48. A sound alarm apparatus for warning persons in the immediate area of a vehicle of the movement of the vehicle, said sound alarm apparatus comprising:
 an electronic signal generating circuit that produces an output broad band sound signal comprising a sound signal of substantially uniform intensity over an audible frequency range that can be processed by a human to locate the source of the signal and excludes pure tonal sound signals and other sound signals that materially affect the dissipation or reduction in noise nuisance of the sound signal of uniform intensity,   a speaker connected only to said electronic signal generating circuit for producing only broad band output sounds comprising sound signals of substantially uniform intensity over an audible frequency range that can be processed by a human to locate the source of the sounds and excludes pure tonal sounds and other sounds that materially affect the dissipation or reduction in noise nuisance of the broad band sound, and   a housing containing said electronic signal generating circuit and said speaker, said housing being configured to be mounted to a vehicle.    
     
     
       49. In a vehicle of the type having an alarm that is automatically activated to warn persons in the vicinity of the vehicle of the potential movement of the vehicle in at least a reverse direction by emitting an audible warning signal, the improvement wherein said alarm comprises an electronic signal generating circuit that produces an audible warning signal consisting of an output broad band sound comprising sound of substantially uniform intensity over an audible frequency range that can be processed by a human to locate the source of the signal and excludes pure tonal sounds and other sounds that materially affect the dissipation or reduction in noise nuisance of the sound of substantially uniform intensity.  
     
     
       50. The combination of claim 49 wherein said alarm is activated when the transmission of said vehicle is placed in a reversing gear.  
     
     
       51. The combination of claim 49 wherein said output broad band sound is emitted in pulsed bursts.  
     
     
       52. The combination of claim 48 wherein said output broad band sound signal comprise pulsed bursts.