GB1586896A - Diaphragm support for a cone type loudspeaker - Google Patents

Description

(54) DIAPHRAGM SUPPORT FOR A CONE TYPE LOUDSPEAKER (71) We, SANSUI ELECTRIC CO.

LIMITED, a Japanese Company of No. 14-1, 2-Chome, Izumi, Suginami-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a diaphragm support of a cone type loudspeaker.

In a known cone type loudspeaker, as illustrated in Figure 1 of the accompanying drawings, a support 3 is positioned so as to support the neck of a cone diaphragm 1, that is to say the support connects the frame to the diaphragm near the apex of the cone in the region where the actuating coil 2 is situated. The particular support 3 shown in Figure 1 comprises a Bakelite (Registered Trade Mark) plate having a number of generally arcuate sectors punched out so as to form what may be termed "butterfly"shaped holes so that the support is known as a "butterfly" support. By means of the punched out holes a plurality of generally radial portion 3a effectively serve to support the neck of the cone diaphragm 1. Screw holes 3b are provided to enable secure fixing of the "butterfly" support 3 onto a frame of a loudspeaker.

This type of support has been found to be suitable when the amplitude of vibrations of the diaphragm is relatively small as the linear response of the support to loads is good. However, during larger amplitude vibrations the supporting portions 3a aTe deformed beyond their elastic limit so that there is a lowering of the linearity of the response characteristic. Furthermore, as the support 3 is made of a material which is not easily fixed in place except by screws, loudspeakers containing such supports can be inefficient to manufacture.

In addition to the so-called "butterfly" supports, it is known to provide corrugated supports 4 such as shown in Figure 2, the supports being formed by a molding having a series of concentric corrugations, the moulding comprising cloth material impregnated with a thermoplastic resin such as phenol resin. Such a corrugated support 4 can easily be attached either to the frame or to the conical diaphragm of the loudspeaker and therefore loudspeakers containing such diaphragm supports are relatively efficient to manufacture by mass production techniques.

In addition however, where the amplitude of vibration of the diaphragm is large the response characteristic has good linearity.

Therefore, such corrugated supports are employed in a wide range of types of loudspeakers. However, when the diaphragm of such a loudspeaker is subjected to only relatively small amplitude vibrations such as those normally associated with a speaker having a butterfly type support the linearity of the response characteristic of the corrugated support is poor.

Therefore, in accordance with the present invention a diaphragm support for supporting the diaphragm of a cone type loudspeaker comprises a first substantially annular part having a radially inner edge portion defining an opening and for connection to the diaphragm, the first part having a linear response characteristic for vibrations of the diaphragm having an amplitude up to a maximum displacement less than the maximum displacement allowed by the first part; and a second substantially annular part having a radially outer edge portion for fixing to the frame of the loudspeaker and a radially inner edge portion connected to or integral with a radially outer edge portion of the first part, the second part having a linear response characteristic for vibrations of the diaphragm having an amplitude in a range extending upwards from the maximum displacement of the diaphragm at which the first part has a linear response. Thus, a loudspeaker may be provided in which the diaphragm support has a linear response characteristic throughout the whole range of amplitudes of the vibrations caused in the diaphragm. The first and second parts may be formed separately and thereafter attached to one another or may be formed integrally with one another.

Two examples of supports according to the present invention, will now be described with reference to the remainder of the accompanying drawings in which : - Figure 3 is a face view of a first diaphragm support according to the invention; Figure 4 is a cross sectional view through the support shown in Figure 3; Figure 5 is a face view of a second support according to the invention; and, Figure 6 is a perspective view of the support shown in Figure 5.

In Figures 3 and 4 there is shown a first example of a diaphragm support 4 which comprises a first inner annular part 41 which is similar to a conventional butterfly type support and is make of Bakelite (Registered Trade Mark). A radially inne redge portion 41b defines a central aperture for the neck of the cone of a loudspeaker and is supported by a radially outer portion which comprises a plurality of arcuate sectors 41a arranged coaxially with the radially inner portion 41b.

The sectors 41a are generally C-shaped to form radially outer edge portions 41c as shown in Figure 3. The support 4 further includes a second annular corrugated part 42. The corrugated part 42 is formed by cloth which is impregnated with resin and moulded into a series of concentric corrugations 42a.

The radially outer edge portions 41c are then bonded to the inner edge of the corrugated section 42 to form the complete support.

With this support 4, and as shown by the phantom line in Figure 4, the radially inner edge portion 41b of the butterfly type section 41 is securely fixed, with adhesive for example, to the neck of a cone type diaphragm 1, whilst the radially outer edge of the corrugated part 42 is securely fixed, by adhesive for example, to the frame F of the loudspeaker.

A loudspeaker with such a support has the following advantages. During small amplitude vibrations, that is to say up to the maximum permitted by the annular part 41, the response characteristic is linear owing to the action of the part 41. During large amplitude vibrations the corrugated part 42 is actuated to maintain the linearity of the response characteristic and in particular so that the various portions of the inner part 41 are not deformed beyond their elastic limit. Due to the formation of the outer section 42 from resin impregnated cloth, the support can be provided with a suitable surface enabling firm fixing by gluing for example, to the frame F, thus avoiding the need for screws which would, of course, take longer and reduce the efficiency of manufacture.

Shown in Figures 5 and 6 is a second example of a support according to the invention. In the second example the inner and outer parts are formed integrally with one another as opposed to the support shown in Figures 3 and 4 where they are formed separately.

To form the support 5 shown in Figures 5 and 6 a thin plate of metal or clothreinforced Bakelite (Registered Trade Mark) is first prepared and this material is then formed with concentric corrugations and has arcuate portions stamped out so as to form slots as shown in Figure 5. Alternatively, where the support material is a thin metal plate, the stamping out of the slots may be carried out first and thereafter the plate corrugated as required. In a third method the punching and corrugating processes may be carried out simultaneously.

It will be appreciated that the step of joining the inner and outer parts of the support is eliminated by an integral construction of the support. The operation of the support shown in Figures 5 and 6 is substantially the same as that shown in Figures 3 and 4, but in addition, the area of the part of the support to be secured to the neck of the conical diaphragm can be increased if desired to increase the security of the connection between them.

WHAT WE CLAIM IS : - 1. A diaphragm support for supporting the diaphragm of a cone type loudspeaker, the support comprising a first substantially annular part having a radially inner edge portion defining an opening and for connection to the diaphragm, the first part -having a linear response characteristic for vibrations of the diaphragm having an amplitude up to a maximum displacement less than the maximum allowed by the first part; and a second substantially annular part having a radially outer edge portion for fixing to the frame of the loudspeaker and a radially inner edge portion connected to or integral with a radially outer edge portion of the first part, the second part having a linear response characteristic for vibrations of the diaphragm having an amplitude in a range extending upwards from the maximum displacement of the diaphragm at which the first part has a linear response.

2. A support according to claim 1, wherein the radially inner edge portion and radially outer edge portion of the first part are connected by a plurality of radially extending bridging sections arranged equi-angularly with respect to one another.

3. A support according to claim 1 or claim 2, in which the second part has a plurality of concentric corrugations.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. characteristic throughout the whole range of amplitudes of the vibrations caused in the diaphragm. The first and second parts may be formed separately and thereafter attached to one another or may be formed integrally with one another. Two examples of supports according to the present invention, will now be described with reference to the remainder of the accompanying drawings in which : - Figure 3 is a face view of a first diaphragm support according to the invention; Figure 4 is a cross sectional view through the support shown in Figure 3; Figure 5 is a face view of a second support according to the invention; and, Figure 6 is a perspective view of the support shown in Figure 5. In Figures 3 and 4 there is shown a first example of a diaphragm support 4 which comprises a first inner annular part 41 which is similar to a conventional butterfly type support and is make of Bakelite (Registered Trade Mark). A radially inne redge portion 41b defines a central aperture for the neck of the cone of a loudspeaker and is supported by a radially outer portion which comprises a plurality of arcuate sectors 41a arranged coaxially with the radially inner portion 41b. The sectors 41a are generally C-shaped to form radially outer edge portions 41c as shown in Figure 3. The support 4 further includes a second annular corrugated part 42. The corrugated part 42 is formed by cloth which is impregnated with resin and moulded into a series of concentric corrugations 42a. The radially outer edge portions 41c are then bonded to the inner edge of the corrugated section 42 to form the complete support. With this support 4, and as shown by the phantom line in Figure 4, the radially inner edge portion 41b of the butterfly type section 41 is securely fixed, with adhesive for example, to the neck of a cone type diaphragm 1, whilst the radially outer edge of the corrugated part 42 is securely fixed, by adhesive for example, to the frame F of the loudspeaker. A loudspeaker with such a support has the following advantages. During small amplitude vibrations, that is to say up to the maximum permitted by the annular part 41, the response characteristic is linear owing to the action of the part 41. During large amplitude vibrations the corrugated part 42 is actuated to maintain the linearity of the response characteristic and in particular so that the various portions of the inner part 41 are not deformed beyond their elastic limit. Due to the formation of the outer section 42 from resin impregnated cloth, the support can be provided with a suitable surface enabling firm fixing by gluing for example, to the frame F, thus avoiding the need for screws which would, of course, take longer and reduce the efficiency of manufacture. Shown in Figures 5 and 6 is a second example of a support according to the invention. In the second example the inner and outer parts are formed integrally with one another as opposed to the support shown in Figures 3 and 4 where they are formed separately. To form the support 5 shown in Figures 5 and 6 a thin plate of metal or clothreinforced Bakelite (Registered Trade Mark) is first prepared and this material is then formed with concentric corrugations and has arcuate portions stamped out so as to form slots as shown in Figure 5. Alternatively, where the support material is a thin metal plate, the stamping out of the slots may be carried out first and thereafter the plate corrugated as required. In a third method the punching and corrugating processes may be carried out simultaneously. It will be appreciated that the step of joining the inner and outer parts of the support is eliminated by an integral construction of the support. The operation of the support shown in Figures 5 and 6 is substantially the same as that shown in Figures 3 and 4, but in addition, the area of the part of the support to be secured to the neck of the conical diaphragm can be increased if desired to increase the security of the connection between them. WHAT WE CLAIM IS : -

1. A diaphragm support for supporting the diaphragm of a cone type loudspeaker, the support comprising a first substantially annular part having a radially inner edge portion defining an opening and for connection to the diaphragm, the first part -having a linear response characteristic for vibrations of the diaphragm having an amplitude up to a maximum displacement less than the maximum allowed by the first part; and a second substantially annular part having a radially outer edge portion for fixing to the frame of the loudspeaker and a radially inner edge portion connected to or integral with a radially outer edge portion of the first part, the second part having a linear response characteristic for vibrations of the diaphragm having an amplitude in a range extending upwards from the maximum displacement of the diaphragm at which the first part has a linear response.

2. A support according to claim 1, wherein the radially inner edge portion and radially outer edge portion of the first part are connected by a plurality of radially extending bridging sections arranged equi-angularly with respect to one another.

3. A support according to claim 1 or claim 2, in which the second part has a plurality of concentric corrugations.

4. A support according to any of claims

1 to 3, wherein the first and second parts are separate and are connected to one another by adhesive.

5. A support according to any of claims 1 to 4, wherein the first and second parts comprise an integral unit.

6. A support according to claim 1, substantially as described with reference to Figures 3 and 4 or Figures 5 and 6 of the accompanying drawings.