GB2306634A

GB2306634A - A combination lamp and alarm unit for vehicles

Info

Publication number: GB2306634A
Application number: GB9613158A
Authority: GB
Inventors: Niall Alastair Duncan Campbell
Original assignee: FLEXIBLE LAMPS Ltd
Current assignee: FLEXIBLE LAMPS Ltd
Priority date: 1995-10-26
Filing date: 1996-06-24
Publication date: 1997-05-07
Also published as: GB9521919D0; GB9613158D0

Abstract

A self-contained combination lamp and alarm unit for a commercial or industrial vehicle, the unit comprising a housing including a lens having a reflector associated therewith, and a sound alarm mounted on a wall of the portion of the housing behind the reflector. The invention benefits in a more compact combination lamp and alarm unit having improved sound output characteristics.

Description

WARNING ALARMS FOR COMMERCIAL OR INDUSTRIAL VEHICLES This invention relates to warning alarms for fitment to commercial or industrial vehicles such as trucks and forklifts.

The hazards of manoevering commercial or industrial vehicles where bystanders are present have led to the widespread use of alarms which emit an audible and visible warning to persons in the vicinity while the vehicle is being manoeuvred. For example, forklift trucks and similar industrial vehicles for use in confined and populated spaces may be fitted with audible alarms and flashing beacons that operate constantly while the vehicle is in use.

Commercial vehicles for the open road such as trucks, buses and coaches have long been fitted with white reversing lamps that have the dual function of illuminating the scene behind the vehicle and providing a visual warning that the vehicle is reversing.

Increasingly, such vehicles also employ back-up alarms to produce an audible alert when the vehicle is reversed. Back-up alarms are necessary because of poor rearward vision from the driver's seat, and warn persons standing behind a reversing vehicle to move out of the way because the driver may not be able to see them. They work even if a bystander fails to see the reversing lamps, and so provide an important element of added safety.

Back-up alarms come in many forms, good examples being in the varied range supplied by an American company, Dominion Automotive Group Inc., under the trade mark TARGET TECH.

Most back-up alarms are electrically powered, being wired into the reversing light circuit of the vehicle to activate when the reversing light comes on. The sound output from such a back-up alarm is usually an intermittent beep, and in order for the beeps to be heard by someone standing behind a reversing vehicle, the output characteristics of the beeps should preferably range in intensity from about 87dB to 112dB with a pulse frequency of 60 to 100 beeps per minute and a signal frequency of between 2 and 3.5 kHz. They may employ magnetic coils but piezo-electric transducers are preferred for their relative compactness, lightness and robustness. However, in order to satisfy the audio output performance requirements piezo-electric transducers used in known back-up alarms still need to be dimensionally large.

Back-up alarms are available as both separate alarm units and as self-contained combination lamp and alarm units. The individual type of units have the sound alarm elements boxed in weatherproof housings, which are attached to a suitable part of the vehicle's structure and then wired into the vehicle's electrical system. As such, their fitment to a vehicle involves additional cost both in terms of buying the unit and in terms of installing it.

The self-contained combination lamp and alarm units, such as those described in WO publication no. 92/01586 to Designtech International Inc. and US 1 958 028 to Aymar, have the sound alarm elements mounted within the same housing as the reversing lamp, thus obviating the need for separate installation of an audio back-up alarm. However, mounting the back-up alarm within the lamp unit housing has a number of drawbacks; the underlying problem is that there is too little room within the lamp unit housing to accommodate sound alarm elements large enough to produce the desired sound output.

Therefore, in known combination lamp and alarm units, the housings are specifically designed to accommodate the sound alarm elements and also have fixtures provided for attaching the elements to the housing; this makes the combination unit housings bulky in size. Also, since sound emitted by the alarm transducer is attenuated by other components within the housing, a larger size transducer has to be selected in order to produce sufficient sound volume, adding to the problem of bulky housings.

In certain combination lamp and alarm units, the housings are specially shaped to aid transmission of, and preferably to amplify, the sound output to the required level. Also, in some units, the housings are provided with an aperture close to the sound alarm unit so that there is less obstruction to the emitted sound, however this makes the units susceptible to ingress of water and contaminants, which risks damaging the electrical components within the unit.

Dominion Automotive Group Inc. also supply a different type of combination lamp and alarm unit, which unit is designed to replace a standard bulb in a reversing lamp and so has a bayonet fitting at one end of the unit and a bulb at the opposite end of the unit.

The central portion of the unit houses control circuitry and a transducer which emits a warning signal when the reversing lamp is activated to illuminate the bulb. The combination unit is an elegant solution but it is not suitable for commercial or industrial vehicles because the unit must be very sniall if it is to replace a bulb; this means that the transducer is too small to produce a loud enough alarm signal for use in commercial or industrial vehicles. This problem is heightened by the muffling effect of the lens and lamp housing that surround the unit when it is fitted to a reversing lamp. Further, the combination unit is inevitably somewhat larger than an equivalent standard bulb, meaning that the filament of the bulb of the combination unit may be displaced from the ideal focal point of the lamp's reflector: if this occurs, it will compromise the performance of the lamp.Also, when the bulb blows, it may be necessary to replace the entire unit at considerably greater expense than an equivalent standard bulb.

The present invention results from our attempts to improve upon all of the prior art outlined above. Accordingly, the invention provides a self-contained combination lamp and alarm unit for a commercial or industrial vehicle, the unit comprising a housing including a lens having a reflector associated therewith, and a sound alarm comprising an alarm transducer, the sound alarm having at least a portion disposed within said housing substantially in alignment with said reflector.

Advantageously, at least a major portion of the sound alarm is disposed within the housing.

As there is no need for a dished bulb holder or reflector tray in the housing at the reflector location, there is a relatively large space in the housing at that location. As a result of the invention, this space, which would otherwise be redundant, is utilised by the sound alarm to allow an optimally compact unit. Moreover, with this arrangement, the housing requires no special shape.

In a preferred embodiment, a portion of the sound alarm extends outside the housing through an aperture in a wall thereof and the sound alarm is clamped to the wall. The portions inside and outside the housing, conveniently, have clamping surfaces which can be advanced towards each other along the portion that extends through the aperture.

Preferably, the clamping surfaces are shoulders and the portion extending through the aperture is in threaded engagement with at least one of the portions inside or outside the housing. The portion outside the housing conveniently consists of or comprises a nut.

In a preferred embodiment, the sound alarm further comprises an alarm circuit electrically connected to the alarm transducer, which, advantageously, comprises a piezoelectric element facing outwardly. In this way, there is no internal attenuation or muffling of the emitted sound, resulting in improved sound output from the selfcontained combination lamp and alarm unit.

In a preferred form of the invention, the lamp/alarm unit is adapted to carry at least one light bulb having bulb contacts being connectable to a voltage source, the arrangement being such that the alarm transducer is activated when the bulb contacts are connected to the voltage source.

Preferably, the housing includes a reflector tray interposed between the reflector and the sound alarm.

Whilst the invention can be applied to any combination of a lamp and an audible alarm, it is particularly appropriate for a back-up alarm; in that case, the lamp unit is a rear lamp unit and the bulb contacts are those of a reversing lamp. The set of bulb contacts may be one of several sets in the lamp unit which may, for example, have five or seven chambers devoted to functions such as direction indicator, brake lamp, stop lamp, reversing lamp and high-intensity fog lamp. A one-piece bulb holder or reflector tray may extend across the unit to serve all of these functions. Optional features include a side marker lamp and a number plate lamp.

Simplest and preferred arrangements have the alarm circuit electrically connected to the bulb contacts such that, when a bulb is fitted between the bulb contacts and is illuminated by connection to a voltage source, the bulb and the alarm circuit are in the same electrical circuit. The bulb contacts and the alarm circuit may be connected in series but are preferably connected in parallel so that the alarm circuit will continue to operate the alarm transducer even if the bulb blows.

Optionally, the alarm transducer and/or the alarm circuit have formations to engage, as a plug-in module, with complementary formations on conductors associated with the bulb contacts.

In order that this invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is an exploded perspective of a sound alarm of a preferred embodiment of the present invention; Figure 2 is schematic perspective view of the sound alarm of Figure 1 mounted on a side wall of a lamp unit housing; Figure 3 is a front view of a lamp unit constructed in accordance with the present invention; and Figure 4 is a sectional view from underneath the lamp of Figure 3.

Referring firstly to Figure 1, the perspective view of a commercially-available sound alarm 10 of a type sold by, for example, Projects Unlimited Audio Alerts and Alarms, shows a cap 111 separated from mounting means 12 formed integral with a body 13 of the alarm 10. The body 13 houses both an alarm transducer 11 in the form of a piezoelectric element, and an alarm circuit 14. The mounting means 12 is in the form of an externally threaded member 120 extending from the body 13 of the sound alarm 10.

The cap 111 has a series of slots 114 penetrating its front face, which slots help to transmit the sound from the alarm transducer 11. A peripheral surface of the cap is knurled, and an internally-threaded skirt allows cap 111 to be screwed onto the threaded member 120.

The body 13 has a pair of contacts (not shown) projecting therefrom, through which electrical power from the vehicle is supplied to the sound alarm 10. The alarm circuit 14 includes such amplifiers, oscillators and other components as are necessary to generate the desired alarm signal, for example a pulse frequency of 60 to 100 beeps per minute, a signal frequency of between 2 and 3.5 kHz and a sound intensity of about 87dB to 112dB when emitted from the alarm transducer 11. Methods of circuit design and possible circuit layouts do not form part of this invention, will be well known to those skilled in the art, and need not be detailed here.

Figures 2 to 4 show a lamp unit 16 to which the sound alarm 10 is fitted to form a selfcontained combination lamp and alarm unit for a commercial vehicle, Figure 2 being a schematic view and Figures 3 and 4 being more detailed. The lamp unit 16 illustrated is a seven-chamber multi-function rear lamp of the type commonly fitted in pairs to the rear of a vehicle such as a truck or trailer. One of the lamp's functions is a reversing light provided by one of its chambers having a white lens portion. The sound alarm 10 is connected to the reversing light circuit to provide a back-up alarm.

The lamp unit 16 comprises a box-shaped housing 18 of rectangular cross-section which is moulded as a single piece from polypropylene. The housing 18 comprises a rectangular back wall 20 and four side walls - two long side walls 22 and two short side walls 24 - which side walls 22 and 24 terminate remote from the back wall 20 in a peripheral front edge 26. The front edge 26 is shaped to define a channel 28 of U-shaped cross-section; this channel 28 accommodates a sealing gasket 30 which is formed as a continuous loop from a water-resistant neoprene material.

Back wall 20 carries four posts (not shown) each of which extends forwardly from the back wall 20 to terminate just forward of the front edge 26 in a circular front surface.

Each post is provided with a threaded bore which extends from the front surface towards the back wall 20. The back wall 20 also carries two spaced external bolts 32 which can be used to fasten the lamp unit 16 to a vehicle.

The housing 18 accommodates a bulb holder comprising a reflector tray 34 which is generally rectangular in plan view and is moulded from a thermosetting plastics material.

The reflector tray 34 is shaped to define a plurality of spaced reflectors 36 which are arranged on a line parallel to the long sides walls 22 of the housing 18. Each reflector 36 has a circular aperture 38 formed therein which extends through the reflector tray 34 from a front surface 40 to a back surface 42 thereof.

The back surface 42 of the reflector tray 34 carries a conducting metal strip 44 which is shaped to provide a side contact 46 in register with each aperture 38. Each side contact 46 comprises a pair of slots (not shown) formed in the strip 44 which slots are shaped to receive radially extending spigots on a bulb 48 in bayonet fashion to hold the bulb 48 such that its filament is disposed at the focal point of reflector 36. The side contact 46 is thereby arranged to contact the side terminal of the bulb 48.

Under each aperture 38, the back surface 42 of the reflector tray 34 also carries a respective conducting plate (not shown) which includes a leaf spring arranged to form a bottom contact to contact the bottom terminal of a bulb 48.

The back wall 20 of the housing 18 is provided with one or more apertures to allow cable access to the conductors within the housing 18 whereby the conductors can be connected to a remote power supply such as a 24V lead-acid battery.

The reflector tray 34 also has four circular holes (not shown) formed therein, each of which extends from the front surface 40 to the back surface 42 thereof and accommodates one of the four posts carried by the back wall 20 of the housing 18, thereby to locate the tray 34 in the housing 18.

The lamp unit 16 further comprises a generally rectangular lens closure 50 which is formed from a transparent plastics material and is fastened to the housing 18 by four screws 52 which extend through apertures formed in the lens closure 50 into the threaded bores in the posts which protrude through the holes in the reflector tray 34. The peripheral edge of the lens closure 50 is coterminous with the front edge 26 of the side walls 22, 24 and the back surface of the lens closure 50 is provided with a peripheral rib 54 which is received in the channel 28. Rib 54 has a depth such that it squashes the sealing gasket 30 accommodated within the channel 28 to form a water-resistant seal between lens closure 50 and housing 18.

Lens closure 50 is divided into a plurality of diffuser lens portions 56, each of which is disposed over a respective one of the reflectors 36. Each diffuser lens portion 56 is formed from a plastics material having a particular colour to provide a special lamp function in conjunction with one of the reflectors 36 and its associated bulb 48. Each diffuser lens portion 56 comprises a plurality of "pillow-case" lenses 58 which are disposed contiguously on each lens portion 56.

In use, light from the filament of a bulb 48 is directed by the associated reflector 36 to form a substantially parallel beam of light which impinges on the associated diffuser lens portion 56. The "pillow-case" lenses 58 disperse the light transmitted by the lens closure 50 over a predetermined angle so that the light from the lamp unit is visible over a required solid angle.

The central portion of the lens closure 50 includes a reflex reflector 60; so there is no bulb associated with this portion of the lens closure and the underlying portion of the reflector tray 34 is not shaped to form a reflector. Instead, as can be seen in Figure 4, this portion of the reflector tray 34 is substantially flat and comparatively shallow in depth where it aligns with the reflex reflector 60. This provides a relatively large space 62 between the reflex reflector 60 and the back wall 20 of the housing 18.

The sound alarm 10 is sited substantially in alignment with the reflex reflector 60.

Whilst Figure 4 shows the sound alarm mounted on the back wall 20 of the housing 18, it is also possible to mount the sound alarm 10 on either one of the two long side walls 22.

The housing has an aperture 64 therein, which in the preferred embodiment is of a diameter between 25 mm and 32 mm. The externally-threaded member 120 of the sound alarm 10 passes through the aperture 64 with the body 13 disposed within the space 62 and with a shoulder of the body 13 bearing against the inner surface of the housing. A portion of the externally-threaded member 120 projects beyond the outer surface of the housing. The internal thread of the cap 111 engages with this projecting portion of the member 120 so that when the cap 111 is screwed fully on to the member 120, an edge 113 of the cap 111 bears against the outer surface of the housing. In this way, by sandwiching or clamping the portion of the housing wall which defines the aperture 64 between the cap 111 and the body 13, the sound alarm 10 is mounted securely in place on the housing.Suitable electrical connections are made between the connectors on the body 13 and the contact set of whichever one of the reflectors 36 serves the reversing light of the lamp unit 16, so that the alarm circuit 14 is activated to drive the transducer 12 when the reversing light comes on.

As a result of this arrangement, not only is efficient use made of space that otherwise would be redundant, but also by locating the alarm transducer on the periphery of the housing it can have maximum audio effect.

Of course, if the reflex reflector 10 was positioned elsewhere on the lens closure 50, it would be entirely possible to move the sound alarm 10 to a corresponding position within the housing 18.

Many variations are possible without departing from the scope of the present invention.

For example, the alarm circuit 14 may be separated from the body 13. A convenient location for the alarm circuit 14 would be in juxtaposition with the contacts associated with the reversing light chamber. The alarm circuit 14 could be made into a plug-in module for flexibility of production. To this end complementary formations on conducting strip 44 and the corresponding conducting plate could be provided to engage with complementary formations on the alarm circuit 14.

As the back-up alarm facility will generally be an optional feature of a vehicle lamp, in cases where the back-up alarm is not required, a push fitting cap or plug (not shown) could readily plug the aperture 64.

The present invention may be embodied in other specific forms without departing from the essential attributes thereof and, accordingly, reference should be made to the appended claims and other general statements herein rather than to the foregoing specific description as indicating the scope of the invention.

Claims

1. A self-contained combination lamp and alarm unit for a commercial or industrial vehicle, comprising a housing including a lens having a reflector associated therewith, and a sound alarm comprising an alarm transducer, the sound alarm having at least a portion disposed within said housing substantially in alignment with said reflector.

2. A unit as defined in claim 1, wherein at least a major portion of the sound alarm is disposed within the housing.

3. A unit as defined in claim 1 or claim 2, wherein a portion of the sound alarm extends outside the housing through an aperture in a wall thereof.

4. A unit as defined in claim 3, wherein the sound alarm is clamped to the wall of the housing.

5. A unit as defined in claim 4, wherein the portions inside and outside the housing have clamping surfaces which can be advanced towards each other along the portion that extends through the aperture.

6. A unit as defined in claim 5, wherein the clamping surfaces are shoulders and the portion extending through the aperture is in threaded engagement with at least one of the portions inside or outside the housing.

7. A unit as defined in claim 6, wherein the portion outside the housing consists of or comprises a nut.

8. A unit as defined in claim 7, wherein the nut is a cap.

9. A unit as defined in any preceding claim, wherein the sound alarm further comprises an alarm circuit electrically connected to the alarm transducer.

10. A unit as defined in claim 9, wherein the alarm transducer comprises a piezo-electric element.

11. A unit as defined in claim 10, wherein said piezo-electric element faces outwardly from said housing.

12. A unit as defined in any preceding claim and being adapted to carry at least one light bulb having bulb contacts being connectable to a voltage source, the arrangement being such that the alarm transducer is activated when the bulb contacts are connected to the voltage source.

13. A unit as defined in claim 12, wherein the unit is a rear lamp unit, the bulb contacts are for a reversing lamp and the alarm transducer, in operation, emits a back-up alarm signal.

14. A unit as defined in claim 12 or 13, wherein the bulb contacts and the alarm transducer are connected in parallel.

15. A unit as defined in any of claims 12 to 14, wherein the alarm transducer and/or the alarm circuit have formations to engage, as a plug-in module, with complementary formations on conductors associated with the bulb contacts.

16. A unit as defined in any preceding claim, wherein the housing includes a reflector tray interposed between the reflector and the sound alarm.

17. A self-contained combination lamp and alarm unit for a commercial or industrial vehicle, substantially as hereinbefore described with reference to or as illustrated in any of the accompanying drawings.