GB2289365A - A sounder having a protective casing - Google Patents

Abstract

A sounder comprises a sound generating device and a protective casing which has integrally formed with it at least one acoustic housing 3, 4. The protective casing may comprise a base 1 and a cover (30 Figure 3) to which may be attached the sound generating device. The sound generator may be a piezoelectric device cooperating with a metal diaphragm. The casing is preferably moulded plastics and has moulded therein a battery holder 14. Slots (44 Fig 3) may be provided for mounting electronic control circuitry. A tamper detecting device may be provided to actuate the sounder if an attempt is made to detach it from its wall mounting or to separate the parts of the casing. <IMAGE>

Description

SOUNDER Field of the Invention This invention relates to a sounder, and more particularly to a sounder comprising a sound generating device and a protective casing.

Background Art Sounders comprising a sound generating device enclosed within a protective casing are well known components of many alarm systems, industrial time signals, door entry systems and similar arrangements.

Conventionally the sound generating device, which may for example be a siren, comprising a metal diaphragm and a plastic acoustic housing, is mounted within a protective casing together with its associated control circuitry.

In alarm sounders the protective casing is required for environmental protection, if the sounder is to be mounted on an outside wall, and also for mechanical protection against vandalism and deliberate sabotage.

A typical alarm sounder to be mounted on an exterior wall may have a protective casing comprising a base plate, onto which the sound generating device or devices and the components of the control circuit are individually mounted, and a cover which may be connected, for example by bolts or screws, to the base plate.

This construction has a relatively large number of components and is relatively costly to produce and assemble.

Summarv of the Invention According to the present invention the sound generating device is integrated with the protective casing to give a sounder which can have fewer component parts, lower cost, faster assembly, increased sound output level for the same power consumption and improved spread of sound power distribution.

In one aspect the invention provides a sounder comprising a sound generating device and a protective casing, in which at least a part of the acoustic housing of the sound generating device is integrally moulded with the protective casing.

The sounder can be an alarm sounder and/or a siren, although the invention is not limited thereto, and any sounder comprising a sound generating device and a protective casing is included within the scope of the invention.

The sound generating device comprises an acoustic housing, which in this invention is formed from a suitable plastics material, and a source of vibrational sound energy, usually a diaphragm, especially a metal diaphragm.

The diaphragm may be for example a piezoelectric sounder element.

The protective casing can, for example, be formed from a plastics material, and may comprise two or more mating parts which are assembled together, for example, with bolts or screws.

One of the parts can comprise a base plate member, and the other a protective cover member, the parts having mating regions. For example, an edge region of the cover member can make sealing engagement with an upstanding wall on the base plate member.

In a preferred embodiment according to the invention, one of the parts of the protective casing, and preferably the base plate member, is moulded integrally with a first part of the acoustic housing of the sound generating device. Preferably the acoustic housing enclosure is formed from two parts, the base plate member and a cooperating second acoustic housing part member, which latter part is enclosed by the cover member in the assembled sounder.

Preferably the sounder also comprises its own electronic control circuitry, and the components for this may be enclosed between the second acoustic housing part member and the cover member, although preferably they are contained in a separate enclosure mounted on the base plate member or, preferably, on the second acoustic housing part member which, in this specification is termed the upper plate member.

The control circuitry preferably comprises an independent power source, for example a battery. The power source may be mounted on or in either of the aforesaid enclosures, but preferably it is mounted on the base plate member, and held in place, for example, by resilient clips.

The protective casing, and especially the base plate member, may be provided with a tamper detection device, which will activate the sounder if, for example, an attempt is made to remove the sounder from its wall mounting and/or to separate the cover member from the base plate member. The device can, for example, comprise a pivotally mounted, spring biased lever switch.

The base plate member may be mounted on an external wall, and a protective cover member adapted to mate with an edge region of the base plate can be provided, which cover is of a size sufficient to embrace the enclosures for the sound generating device and the electronic components, and the power source.

By integrating the sound generating device with the protective casing it is possible to adapt the size of the acoustic housing to the casing, thus making the best use of the space available.

The plastics material component parts of the sounder may be integrally moulded by any suitable plastics moulding technique, although injection moulding is generally preferred.

Brief Description of the Drawings An embodiment of the invention will now be described by way of example with reference to the accompanying Drawings in which: Figure 1 is a perspective view from one side of a base plate member of a sounder according to the invention integrally moulded with two lower part acoustic housings; Figure 2 is a plan view of the base plate member of Figure 1; Figure 3 is a perspective view from one side of an upper plate member of a sounder according to the invention having two upper part acoustic housings integrally moulded therein; Figure 4 is a plan view of the upper plate member of Figure 3; Figure 5 is a side elevational view of the upper plate member of Figure 3 partly in section; Figure 6 is an end elevational view of the upper plate member of Figure 3 partly in section;; Figure 7 is a perspective view from one side of an assembled sounder according to the invention with the protective cover member removed; Figures 8 to 11 are respectively a plan view, a side elevation, an end elevation and a perspective view from above and one side of a piezoelectric element holder for use in a sounder according to the invention; Figures 12 to 15 are respectively a plan view, a sectional side elevation, an end elevation and a perspective view from above and one side of an enclosure for the circuitry of a sounder according to the invention; Figure 16 is a perspective view from above and one side of a protective cover member for a sounder according to the invention; and Figure 17 is a perspective view from above and one side of an assembled sounder according to the invention.

Detailed Description of the Drawings Referring first to Figures 1 and 2, the base plate member 1 comprises an injection moulded plastics member having a floor 2 integrally moulded with a pair of lower part acoustic housings 3, 4. The part acoustic housings each have circular peripheral walls 5, 6 and twenty radially extending vanes 7. Within the peripheral walls 5, 6 the part acoustic housings have concentric baffles 8, 9, and 10, 11 respectively and conical deflectors 12, 13 respectively. All these parts are integrally moulded with the floor 2.

Also moulded in the floor 2 is an elongate depression forming a semi-circular battery holder 14, with resilient retaining clips 15, 16. A pivot 17 and support 18, for a tamper detecting device are also provided.

Upstanding internally threaded boss members 19 are provided around the peripheral walls 5, 6 for securing the upper plate member to the base plate member, and recessed mounting holes 20 are provided for securing the base plate to a vertical wall.

The base plate member 1 is also provided with a peripheral wall member 21 which serves to locate a protective cover. The cover engages in a recessed slot 22 and is held by a screw which is received by a threaded hole 23 in an upstanding projection 24.

Turning now to Figures 3 to 6, the upper plate member 30 comprises a floor 31 having integrally moulded therewith a pair of upper part acoustic housings 32, 33.

The upper part acoustic housings have concentric baffles 34, 35, 36, and 37, 38, 39 respectively moulded into the under surface of the upper plate member 30, and boss members 40 for mounting a support member for a piezoelectric sounder element (see Figure 7) on each of the upper part acoustic housings.

To the top surface of the upper plate member 30 are integrally moulded a pair of resilient mounting posts 41.

Slots 44, are cut in the floor 31. These are respectively for mounting and positioning the enclosure for the electronic control circuitry (see Figure 12).

Further pairs of mounting posts 42,43 are provided for securing a PCB to the upper plate member.

Referring now to Figure 7, there is shown an assembled alarm sounder incorporating the base plate member of Figures 1 and 2 and the upper plate member of Figures 3 to 6, but without the protective cover.

The base plate member 1 is attached to the upper plate member 30 by screws 50 which are screwed into boss members 19. Piezoelectric element holders 51, (of which only the left hand holder is shown) are attached to each upper acoustic housing 32, 33 by means of screws passing through boss members 40 and 52. The piezoelectric sounder element (not shown) is located in the cavity formed between the holder 51 and the upper acoustic housings 32, 33. A battery 53 is placed in the battery holder 14 and is held in place by the clips 15, 16 (Figure 1). A pivotally mounted lever type microswitch 54 is mounted on the pivot 17 and protrudes through a hole 55 in the floor 2 of the base plate member 1. A post 56 protrudes through a hole 57 in the upper plate member 30 and rests against the microswitch 54 and the protective cover 90 (see Figure 16).The microswitch 54 is balanced such that if either the entire casing is prised away from its wall mounting, or the protective cover is lifted away from the base plate, its contacts are opened and the alarm circuitry is thereby activated.

A rectangular enclosure 58 is mounted on the upper plate member 30, and is retained in place by a screw 59, by lugs 60 (see Figure 14) which fit into slots 44, and by a pair of mounting posts 41, which cooperate with shoulders 61 on the external wall of the enclosure. The enclosure contains the electronic circuitry for the operation of the sounder.

Positioned over the left hand (as viewed in the drawing) piezoelectric element holder 51 is a translucent cover 62, which embraces a xenon warning lamp mounted on the holder 51, the details of which can be more readily seen from Figures 8 to 11.

In Figures 8 to 11 there is shown the left hand piezoelectric element holder 51, having boss member 52 surrounding screw holes for mounting the holder on the upper plate member 30, and having on its lower surface a piezoelectric element 70 (illustrated diagrammatically by broken lines). On the top surface of the element holder 51 a wire harness 71 leads wires 72 to the piezoelectric element 70, and a xenon lamp 73 is held in place by a lamp holder 74. Adjacent the xenon lamp is mounted an inclined reflective surface 75.

The right hand piezoelectric element holder is similar by construction except that the xenon lamp and reflective surface are omitted.

In Figures 12 to 15 there is shown in more detail the enclosure 58 for containing the electronic circuitry for the operation of the sounder. The enclosure itself is injection moulded from a suitable plastics material and is of generally rectangular shape. The enclosure is provided with a pair of lugs 60 which fit into slots 44 in the upper plate member 30, and is secured by means of a screw 80 passing through a hole 81 in the edge region of the enclosure to the upper plate member 30. the enclosure has shoulders 61 which cooperate with locating posts 41 to assist in locating and retaining the enclosure 58 on the upper plate member 30.

Figure 16 shows the protective cover member 90 which cooperates with the base plate member 1 to form the protective casing for the sounder. The cover 90 is formed from a tough opaque injection moulded plastics material and has an elliptical orifice 91 for receiving the translucent lamp cover 62. The lamp cover 62 is connected to the protective cover member 90 by means of screws which are received in hollow threaded posts 92.

At one end the protective cover has a hole 93 for receiving a retaining screw 94 (see Figure 17) which passes through the cover and is received in hole 23 in projection 24 of the base plate member. At the other end, a tongue 95 is received in recessed slot 22 of the base plate member.

The assembled sounder is illustrated in Figure 17.

The reader's attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps or any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Claims (12)

1. A sounder comprising a sound generating device and a protective casing, in which all or part of the acoustic housing of the sound generating device is integrally moulded with the protective casing.

2. A sounder according to claim 1, in which the sounder is an alarm sounder or siren.

3. A sounder according to claim 1 or 2, in which the protective casing is formed from a plastics material and comprises two or more mating parts which are assembled together.

4. A sounder according to claim 3, in which the protective casing comprises a base plate member and a protective cover member.

5. A sounder according to claim 3 or 4, in which a first mating part of the protective casing is moulded integrally with a first part of the acoustic housing of the sound generating device and a cooperating second part of the acoustic housing is enclosed by the second mating part of the protective casing.

6. A sounder according to Claim 5, in which the first mating part is the base plate member and the second mating part is the protective cover member.

7. A sounder according to any of the preceding claims, which comprises electronic control circuitry contained in a separate enclosure.

8. A sounder according to claim 7, in which the control circuitry comprises an independent power source.

9. A sounder according to any of the preceding claims, in which the protective casing is provided with a tamper detecting device.

10. A sounder according to any of the preceding Claims which is provided with a warning lamp.

11. A sounder according to any of the preceding claims substantially as hereinbefore described with reference to and as illustrated in the accompanying Drawings.

12. A sounder substantially as hereinbefore described.