GB2205676A

GB2205676A - Audible warning device

Info

Publication number: GB2205676A
Application number: GB08810330A
Authority: GB
Inventors: George Albert Willi Sturtivant; William Cruickshank; D Lally; Kieth Roberts
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-04-29
Filing date: 1988-04-29
Publication date: 1988-12-14
Also published as: GB8810330D0; GB8710079D0

Abstract

An audible warning device comprises a sound emitting unit 1 including a signal generating unit 7 for generating a sound signal and a manually adjustable attenuating unit 8 which provides for the emission of sound signals at varying levels so that the same sound emitting unit can be used in different ambient conditions. The attenuating unit may adjust the volume of the sound signal either continuously or stepwise. The audible warning device may be combined with a flashing light, and may be used to alert blind pedestrians of hazards in their path. <IMAGE>

Description

IMPROVEMENTS RELATING TO WARNING DEVICES This invention relates to warning devices and particularly audible warning devices used to alert blind pedestrians of hazards in their path.

Hithertofore in full daylight road cones have been used to alert pedestrians of obstacles in their path. At night or in poor light flashing warning lights are used. Recently and for the purpose of warning blind pedestrians the latter warning lights have been fitted with audible warning units as described in UK Patent KO tlGaoow Where such audible warning units are used they may be in the form of a sound emitting unit which emits a single intermittent signal or a sound emitting unit where the volume of the signal is automatically adjustable in accordance with ambient sound.

A sound emitting unit which emits a single signal has the disadvantage of not being responsive to variable sound conditions and whilst it may emit a signal which may be heard in a noisy down-town area such a signal may be considered too loud in a quiet residential area. This necessitates the production of different warning units for specific areas of use. Where a self-adjusting sound emitting unit is used this may not be fully responsive to the complexities of the ambient sound conditions, thence, although the volume of ambient sound may be the same in two different areas the frequency mix of the sound in one area may be such that a louder signal is required in that area.

The present invention overcomes the above problems and provides for the use of a single warning device suitable for most situations which is adapted to be responsive to all elements of its ambient conditions and not just volume.

According to the present invention an audible warning unit comprises a sound generating unit for emitting an audible warning signal, the sound generating unit being associated with a sound control unit which is manually adjustable to provide at least two levels of emission of the audible warning signal.

According to a feature of the invention the sound control unit may include a manual switch which may be set to a plurality of discreet positions. Alternatively the sound control unit may have a proportional control such that the output of the device may be set at any level within a given range.

In a further form the invention may be in the form of an audio/ visual warning device wherein the audible warning unit is combined with a flashing light. In such a form the warning light and the audible warning unit could be readily detachable for separate use if required.

Advantageously, the audible warning unit is waterproof.

The audible warning unit, either separately or combined with a flashing warning light, may be adapted to operate from either a battery supply or a suitably modified mains supply.

An audio/visual warning device in accordance with the invention will now be described by way of example only, with reference to the following figures of which: Figure 1 is a Sectional Elevation of the audio/visual warning device and Figure 2 is a circuit diagram of the attenuating unit 8 of the device.

The audio/visual warning device comprises a sound emitting unit 1 forming part of a flashing warning light 2. Both the sound emitting unit 1 and the flashing warning light 2 are operable from a common battery 3.

The sound emitting unit 1 comprises a waterproof speaker 4 which is sealed within a housing 5 which has perforations 6 for sound emission. The speaker 4 is connected to a signal generating unit 7 which produces an electrical wave form of set frequency. Interposed between the speaker 4 and the sound generating unit 7 is a sound attenuator 8.

Referring to Figure 2 the attenuator 8 comprises a transducer 9 and a transducer 10 which may be switched from series to parallel operation to provide for two sound emissions of discreet volume.

The alternator circuit illustrated derives the input signal from the signal generating unit 7 and the circuit is operable from a coupled switch 11.

In operation a signal will be generated from the signal generator 7 which will be placed in circuit with the battery 3 along with the flashing warning light 2. The signal is transmitted to the sound attenuator 8. With the switch 11 in position A and assuming the impedance of both transducers 9 and 10 to be Z then the power (P1) delivered by the transducers will be Pl = 2 2 V = (z7) 2 Where V is the voltage of the input signal from the generating unit 7.

When switch 11 is moved to position B the power (P2) deliverable by the transducers will be: P2 - 2Z Hence the change in power level to be transferred to the speaker 4 will be in the ratio of: Pl =(2v /Z)P2 = 4P2 (vt/2z) Hence the level of output from the speaker 4 can be increased by a factor of four if required.

Although only one form of sound attenuator has been described it should be appreciated the attenuator 8 can provide for a multiplicity of choice on output levels by providing for variable taps on a standard impedance. Such taps being either proportionate or discreet.

Alternatively the supply voltage can be adjustable.

In the case of pulsed signals the perceived amplitude level can be changed by reducing the period during which the pulse is emitted.

The perceived loudness heard by the human ear changes when this period is within the region of 0.1 seconds and the sound attentuating device may take the form of a frequency adjusting unit.

In a further alternative form the attenuating unit may be of a mechanical nature whereby the perforations 6 are manually adjustable in size.

As well as having a multiplicity of sound levels the warning device can be designed to operate more than one speaker system.

Ideally two speakers could be oppositely mounted to ensure that the warning device would not be ineffective, as it would otherwise be if a single speaker system were inadvertibly placed to direct its signal away from the path of a prospective hearer.

Advantageously speakers could be added or subtracted from the warning device by using suitable plugs and sockets. The sound emitting unit 1 could be similarly detachable and available for use either separately or together with the flashing warning light Although the specific embodiment has been described with reference to a battery power source the invention as described is suitable for use with a safe mains supply.

Claims

1. An audible warning unit comprising a sound generating unit for omitting an audible warning signal the sound generating unit being associated with a sound control unit which is manually adjustable to provide at least two levels of omission of the audible warning signal.

2. An audible warning unit as claimed in claim 1 which may be set to a plurality of discreet positions.

3. An audible warning unit has claimed in claim 1 in which the sound control unit includes a proportional control such that the output of the warning unit may be set at any level within a given range.

4. An audible warning unit as claimed in any of the preceding claims which is combined with a flashing light to provide audio/visual warnings.

5. An audible warning unit as claimed in claim 4 combined with a readily detachable flashing light.

6. An audible warning device as claimed in any one of the preceding claims which is waterproof.

7. An audible warning device as claimed in any one of the preceding claims which is adapted to operate from either a battery supply or a suitably modified mains supply.