GB2187608A

GB2187608A - Loudspeaker for an alarm system

Info

Publication number: GB2187608A
Application number: GB08702673A
Authority: GB
Inventors: Pedro Altimira Vinallonga
Original assignee: Plastmetal SA
Current assignee: Plastmetal SA
Priority date: 1986-03-05
Filing date: 1987-02-06
Publication date: 1987-09-09
Also published as: GB8702673D0; FR2595497B1; PT84374A; ES292736U; PT84374B; ES292736Y; FR2595497A1

Abstract

A loudspeaker for an alarm system consists of a frusto-conical diaphragm 1 fixed at its periphery 2 to a support casing 4 and a domed diaphragm 5 placed between the casing 4 and a motor unit 11 with the domed part extending through a central opening 7 in the casing 4 and partly extending into the frusto-conical diaphragm 1, which is joined to the domed diaphragm in the region of the smaller end of the frusto- conical diaphragm, so that the dome is partially lodged in the interior of the frusto-conical diaphragm 1. <IMAGE>

Description

SPECIFICATION Loud Speaker for an Alarm System This invention relates to a loud speaker for use in producing an audible alarm.

The loud speaker may be used with any type of alarm system, for example a vehicle alarm system, internal and external alarm systems for security installations for all types of buildings, and for other systems such as fire detection, robbery, animal movement, etc.

An embodiment of the invention provides a loud speaker having a large dynamic output in decibels with minimum energy consumption, of small size and low cost, for which reason the design has been carefully made to obtain economical manufacturing, a small number of parts, and easy and simple mounting.

In alarm systems of any type used to date, conventional loud speakers have been used which gave little power and very low output. This known type of speaker uses a truncated cone membrane or diaphragm of low quality, since a musical type curve was not sought; however the cost is high because it must be large in order to give a strident sound and adequate range.

According to the present invention there is provided a loud speaker for an alarm system, comprising two diaphragms or membranes, one being frustro-conical and held at its periphery to a support member having an opening and the other being a domed diaphragm or membrane placed between the support member and a motor unit, with the domed part of the diaphragm or membrane extending through the opening in the support member and partly extending into the frustroconical membrane which is joined to the domed diaphragm or membrane so that the dome is partially lodged in the frustro-conical interior of the frustro-conical diaphragm or membrane.

With the speaker proposed by this invention, two complementary effects are obtained; sharp, penetrating, high frequency sounds are obtained which can be heard above any other, and also medium or low frequency sounds, the latter generated by the frustro-conical diaphragm or membrane which is attached to the domed diaphragm or membrane which produces the high frequency sounds. In this way, greater range is reached without increasing the power consumption of the loud speaker.

The support member, with the usual means for fixing the speaker in the place where it is to be seated, also preferably has centering pins to ensure the correct positioning of the domed diaphragm or membrane.

On the other hand, the domed diaphragm or membrane is held between the support and the motor unit by conventional holding elements, for example screws passing through the said support and domed diaphragm or membrane, which are in engagement with the motor unit.

Also of note is the provision on the said domed diaphragm or membrane of means for centering the same with respect to the motor unit coil, and of means to fix the support to the said motor unit, which is effected before mounting the frustroconical membrane.

An embodiment of the present description will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of dynamic speaker for alarms, in accordance with the present invention, in which both the frustro-conical diaphragm or membrane and the casing supporting the same are partly in section to clearly show their profile; and Figure 2 is a schematic detail in cross-section showing the coupling between the two diaphragms or membranes used in the speaker.

From these figures it will be observed that the loud speaker is made up of a frustro-conical diaphragm or membrane 1, which through its peripheral position 2 is fixed to a recess 3 provided in a support 4 intended as a physical support for the whole loud speaker and having for this reason conventional means for fixing it to any required structure.

In collaboration with the frustro-conical diaphragm or membrane 1 is a domed diaphragm or membrane 5 which, in the context of the speaker, is partially situated under the casing 4, fitting by its peripheral lip 5' to the lower face of the base 6 of the casing 4, while the dome 5 extends into the casing 4 through a central opening 7 therein, fitting partially within the frustro-conical diaphragm or membrane 1, as may be seen in detail in Figure 2, in such a way that the said frustro-conical diaphragm or membrane 1 is associated with the domed diaphragm or membrane 5 to which it is fixed by the edge of the smaller opening 8 in the diaphragm 1.

Starting with this basic structure and in order to facilitate the mounting of the various elements making up the loud speaker, the casing 4, specifically on the lower face of its base 6, has centering pins 9 for the domed diaphragm or membrane 5, and holes for receiving screws 12 fixing this to a motor unit 11. The screws 12 pass through the holes 10 and also pass through holes 13 provided in the peripheral lip 5' of the domed diaphragms or membranes, which screws 12 then engage in holes 14 provided in the motor unit 11.

This motor unit 11 is conventionally formed by a coil 15, a poled core 16, a magnet 17 and the metallic discs 11, making up the whole of the motor unit.

It should also be pointed out that in the domed diaphragm or membrane 5, surrounding the dome 5 itself and provided on the inside area of the peripheral lip 5', there is an annular ring portion 18 that acts for self-centering the diaphragm or membrane 5 with respect to the coil 15 of the motor unit 11.

In turn, the motor unit 11 is perfectly centered with respect to the casing 4 since, on the latter and corresponding to the externai periphery of the base 6, is a flange 19 which is clearly visible in Figure 1.

Lastly, the support 4 includes holes 20 for the passage of cables 21 from the coil 15 to the frustroconical diaphragm or membrane 1.

In this way, a double sound effect is produced, that is the emission of high frequency sounds on the one hand and medium frequency sounds on the other, through the domed diaphragm or membrane 5 and the frustro-conical diaphragm or membrane 1, while the various elements making up the loud speaker are easily intercoupled, first by fixing the casing 4 of the motor unit 11, inserting the domed diaphragm or membrane 5, and then fixing the frustro-conical membrane 1.

It is not considered necessary to make this description more extensive as any expert in the field will understand the invention and the advantages derived from the same.

The materials, shape, size and layout of the elements may be varied without departing from the invention as defined in the appended claims.

Claims

1. A loud speaker for an alarm system, comprising two diaphragms or membranes, one being frustroconical and held at its periphery to a support membrane having an opening and the other being a domed diaphragm or membrane placed between the support member and a motor unit, with the domed part of the diaphragm or membrane extending through an opening in the support member and partly extending into the frustroconical membrane which is joined to the domed diaphragm or membrane so that the dome is partially lodged in the frustro-conical interior of the frustro-conical diaphragm or membrane.

2. A loud speaker as claimed in claim 1, in which the opening is surrounded by a recess step in which the periphery of the frustro-conical diaphragm is received.

3. A loud speaker as described in claim 1, in which the casing has centering pins for the domed diaphragm or membrane and in which the said membrane is held between the said casing and the motor by securing elements before the mounting of the frustro-conical diaphragm or membrane, and the domed diaphragm or membrane includes selfcentering means which engage the coil of the motor unit.

4. A loud speaker for an alarm system, substantially as hereinbefore described with reference to any as illustrated in the accompanying drawings.