WO1997017817A1

WO1997017817A1 - Supporting electronic equipment

Info

Publication number: WO1997017817A1
Application number: PCT/GB1996/002720
Authority: WO
Inventors: Yasuo Yamamura
Original assignee: Yamamura Churchill Limited
Priority date: 1995-11-06
Filing date: 1996-11-06
Publication date: 1997-05-15
Also published as: GB9522691D0; GB2307024A; GB2307024B

Abstract

A support for audio equipment, in which an upper supporting portion is mounted on a base via a low-friction bearing containing ball-bearings. The low-fiction bearing allows free vibration of the upper supporting portion, and therefore the equipment mounted thereon, in a horizontal direction, thereby isolating horizontal vibrations produced in the audio equipment from the base of the support.

Description

SUPPORTING ELECTRONIC EQUIPMENT

This invention relates to supporting electronic equipment. More particularly but not exclusively the invention relates to a set of supports for, and a method of supporting, electronic equipment, such as loudspeakers.

Until the present time, the loudspeakers of hi-fi systems have been mounted in various manners. To achieve a high quality of reproduction of sound it has conventionally been believed that loudspeakers should be mounted on stands which are relatively robust and solid. This provides for some fidelity of reproduction insofar as the loudspeaker stands are used to cut out undesirable resonant vibrations which are set up in the loudspeaker including its housing.

However, one drawback of known supports for loudspeakers is that the support will transmit vibrations from the loudspeaker itself into the surrounding materials. Thus, sound vibrations are transmitted to the floor, walls and ceiling of a room in which a hi-fi system is being played. The floor, walls and ceilings of a room generally have resonant frequencies of 20-80 Hz and vibrations at their resonant frequencies will be amplified in the room. There are various problems associated with the transmission of vibrations from audio equipment via its supports. Sound travels faster in solid materials than the atmosphere, and takes circuitous routes when transmitted via solid materials between the loudspeakers and the ear of the listener. Sound vibrations created by a speaker and transmitted via solid matter can audibly interfere with the sound created by the loudspeaker and transmitted directly by the atmosphere.

Furthermore, vibrations set up in solid material on which audio equipment is mounted can cause distortion of the output from the equipment because of the effects of the vibrations within the equipment. The performance of loudspeakers themselves can be interfered with by resonant and other vibrations which can cause the loudspeaker output to be degraded.

Known methods of attempting to overcome those problems include adding weight and solidity to the loudspeaker, and mounting a loudspeaker using conical supports. However, the transmission of some vibrations, in particular high frequency vibrations, cannot be properly suppressed simply by these methods. Furthermore, the loudspeaker suffers from significant reactive forces when mounted in such manners.

Flexible supports such as rubber or air suspension can reduce the transmission of vibrations from a loudspeaker to the surrounding solid environment. However, such a flexible mounting provides a speaker with excessive freedom of vibration. Vibrational degrees of freedom are provided in the form of three linear movements along the x, y and z axes and the three rotational modes of vibration around each of these three axes. Interference between vibrations operating in these six degrees of freedom produces further vibrational modes. As a result, flexible mountings allow a loudspeaker and its housing to resonate at a large number of resonant frequencies and the performance of the loudspeaker is degraded.

United States patent 5,253,841 describes apparatus for supporting a printing apparatus which is intended to isolate vibrations caused by lateral movement of the printing head from other associated instruments. Rollers are attached to the base of the printing apparatus and are mounted to reciprocate on arcuate guide grooves. Thus, in use the movement of the printing apparatus provided by the rollers has both horizontal and vertical components.

In accordance with one aspect of the present invention, there is provided a method of mounting electronic equipment, said method comprising providing a support comprising a base and an upper supporting portion on which the electronic equipment is mounted, allowing said upper supporting portion to vibrate freely with respect to said base, and limiting said free vibrations substantially within a horizontal plane, thereby isolating horizontal vibrations created in the electronic equipment from the base.

By allowing such free vibrations and limiting the free vibrations within a horizontal plane, horizontal vibrations created in the electronic equipment are effectively isolated from the surrounding environment. Furthermore, since the horizontal vibrations are limited within a horizontal plane, the electronic equipment is not subject to reactive forces when undergoing vibrations in the direction of free vibration. Such reactive forces can have an effect on the performance of electronic equipment. For example, if a loudspeaker were mounted to allow a degree of movement in the vertical direction, which is caused in response to the horizontal vibrations created in the loudspeaker itself, the vertical movement would cause a reactive force in the loudspeaker which may distort its output.

In some cases, the free horizontal vibrations of the upper supporting portion with respect to the base are limited substantially within a linear direction. This isolates vibrations created in the equipment in the same direction, whilst inhibiting the creation of multidirectional nodes of vibration whereby resonance of the equipment could occur.

Where the electronic equipment has a main direction of vibration, for example where the electronic equipment is a loudspeaker, the allowed linear direction of free vibration is preferably aligned with that main direction of vibration of the equipment. In other cases, where the equipment vibrates in different horizontal directions, for example where the electronic equipment is a record turntable or CD player, the supporting portion may be allowed to vibrate freely with respect to the base in different horizontal directions.

According to a further aspect of the invention there is provided a support for electronic equipment, said support comprising a base and a free-standing supporting upper portion mounted on the base by a ball-bearing constrained to roll freely substantially within a horizontal plane, thereby isolating horizontal vibrations created in the electronic equipment from the base.

The use of a ball-bearing constrained to roll freely substantially within a horizontal plane provides for a low-friction bearing which is particularly effective in isolating vibrations in the support.

Further features and advantages of invention will become apparent from the following descriptions.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying diagrams, wherein:-

Fig. 1 is a perspective view of a set of supports embodying the present invention; Fig. 2 is a plan view of a portion of a loudspeaker supported by the set of supports illustrated in Fig. 1;

Fig. 3 is an exploded perspective view of one of the supports shown in Fig. 1; and

Fig. 4 is an exploded perspective view of another of the supports illustrated in Fig. 1;

Fig. 5 is a perspective view of a support according to a further embodiment of the invention; Fig. 6 is a side view of the support shown in

Fig. 5;

Fig. 7 is an exploded perspective view of the support shown in Figs. 5 and 6;

Fig. 8 is a perspective view of a support according to a further embodiment of the invention;

Fig. 9 is a sectional view across line A-A in Fig. 8;

Fig. 10 is a perspective view of a support according to a yet further embodiment of the invention; and

Figs. 11 and 12 are sectional views across lines B-B and C-C respectively in Fig. 10.

Referring to Fig. 1, a set of supports embodying the invention comprises a linear bearing support 2 (which allows low-friction motion in a linear horizontal direction only) and two planar bearing supports 4 (which allow motion in any direction in a horizontal plane) . The supports can be arranged in various manners in order to provide support to audio equipment as required. There is however a preferred manner of arrangement in which the supports are arranged relative to one another as shown in Fig. 2.

A loudspeaker 6 is placed upon the supports 2 and 4 when they are arranged in a triangular array, with the linear bearing support 2 supporting the front 8 of the loudspeaker and the planar bearing supports 4 supporting the rear of the loudspeaker.

In order to understand the construction of the supports, reference should be made to Figs. 3 and 4. Consider first the linear bearing support 2 which has a circular wooden or steel base 10 and a circular wooden or steel top 12. Two ball-bearings 14 and 16 are borne between the base 10 and the top 12. The ball-bearings may typically have a diameter of 7mm, although ball-bearings of any suitable diameter may of course be used. The ball-bearings 14 and 16 move along a linear path defined by triangular grooves 18 and 20 in the base and top respectively. Whereas the body of the base and top may be formed of wood, steel or other rigid material, groove 18 is preferably defined by a metal such as steel. Groove 20 is also similarly defined. It is to be said that other relatively hard materials could instead be used. The ball-bearings 14 and 16 are constrained to travel only short distances within the grooves 18 and 20 by means of central stops 22 and 24 located in the middle of the grooves, and end stops 26 and 28 located at the ends of the grooves. The ball-bearings 14 and 16 are thus located towards the outer periphery of the support 2 to provide even balance in use.

A metal rod 30 of small diameter is located in a shallow groove on the lower surface of the base 10, such that when the base is level (as it should be in use) , the metal rod 30 fully supports the base when placed on a flat horizontal surface. The rod 30 may typically have a diameter of 2mm although of course a rod of any suitable diameter may be used. The rod 30 is disposed at right angles to the groove 18.

With regard to Fig. 4, each of the planar bearing supports 4 comprise a top 32, a middle portion 34 and a base 36. The top 32 consists of a circular metal disc 38 and a metal annular ring 40 bonded concentrically to the base of the disc 38. The annular ring 40 therefore defines a circular flange against which a ball-bearing 42, held between the top 32 and the middle portion 34, abuts.

The middle portion consists of a circular body 44 which may be made of wood or steel and has a cylindrical hollow 46 on its upper surface. A metal annular ring 50 is located within the hollow 46. A metal plate 52 is located beneath the annular ring 50. Thus, a lower circular flange against which the ball¬ bearing 42 abuts is defined by the annular ring 50. When the support is assembled and in use, the ball- bearing 42 bears the entire weight above it and is contacted above and below by metal plates 38 and 52. This is advantageous in that it provides for low frictional resistance in the bearing and in that the point-like contact made by the ball-bearing is effective in inhibiting the transmission of relatively low-frequency vibrations. Although in the illustrated embodiment only one ball-bearing 42 is used in each support 4, more than one ball-bearing could equally well be used. The base 36 has a circular foot 54 and an upstanding threaded member 56 which threadingly engages with a bore 58 located on the underside of the middle portion 34. The height of the support 4 is adjustable by rotation of the middle portion 34 with respect to the box 36.

When assembled, the supports appear as shown in Fig. 1. Furthermore, when used to support a speaker, the grooves 18 and 20 are aligned as illustrated in Fig. 2 to allow the loudspeaker a freedom of movement which is parallel to the direction of vibration of the loudspeaker membrane (hereinafter referred to as the x-axis) . Because the ball-bearings 14 and 16 in the grooves 18 and 20 and the ball-bearings 42 of the supports 4 in the annular rings 40 and 50 offer a low- friction motion, the loudspeaker is effectively entirely free to move along the x-axis, i.e. backwards and forwards. This movement is of course within the constraints of the length of the groove portions in which the ball-bearings 14 and 16 move and the diameter of the inner flanges of the rings 40 and 50.

When the loudspeaker 6 is used to reproduce an input signal, the x-axis vibrations produced by the loudspeaker are isolated by the supports 2 and 4 and are not transmitted from the loudspeaker 6 via the supports 2 and 4 to the floor or other surface on which the loudspeaker is mounted. The use of ball¬ bearings within the support reduces the contact between the upper and lower portions substantially to a point, which further reduces the scope for transmission of horizontal vibrations between the loudspeaker 6 and its surroundings. Similarly the rod 30 reduces the transmission of rotational vibrations in the direction of the x-axis by providing a rotational degree of freedom about an axis substantially horizontal and perpendicular to the x- axis (hereinafter referred to as the y-axis) . At the same time, vibration of the loudspeaker along and about other axes is inhibited because there is no freedom of movement along or about any other axis. As a result, the supports 2,4 inhibit a large amount of the resonance which would otherwise occur at various frequencies within the loudspeaker housing.

It is to be noted that the bearing supports need not be constrained to move only linearly. An arrangement which allows low-friction motion along both the x-axis and the y-axis may be employed.

A third embodiment of support as illustrated in Figs. 5-7 might be utilised, preferably in a set of supports. The support illustrated will be referred to herein as an x, y bearing support 60. The x, y bearing support consists of a lower steel plate 62, a middle steel plate 64 and an upper steel plate 66. Middle plate 64 is mounted above lower plate 62 in a similar fashion to the mounting of top 12 with respective base 10 of the embodiment shown in Figs. 1- 3. The middle plate is free to move in the x direction. Triangular grooves 68 are formed coaxially along a line disposed parallel to the x axis in the upper surface of lower plate 62, and corresponding triangular grooves 70 are formed in the lower surface of middle plate 64. Steel ball-bearings 72 roll freely within grooves 68 and 70. Furthermore, top plate 66 is free to move in the y direction with respect to middle plate 64 by means of a similar mounting. Triangular grooves 74 are formed coaxially along a line parallel to the y axis in the upper surface of middle plate 64. Corresponding triangular grooves 76 are formed in the lower surface of upper plate 66. Ball-bearings 78 move freely, ie without significant frictional resistance, within grooves 74 and 76.

A retaining shaft 80 is fixed in the centre of middle plate 64, protruding from both its upper and lower surfaces. A threaded bore is formed in each end of the retaining shaft. An elongate aperture 82 is formed in lower plate 62 extending coaxially with grooves 68 and parallel to the x axis. Similarly, an elongate aperture 84 is formed in the upper plate 66, coaxially with grooves 76 and extending in a direction parallel to the y axis. When assembled, a screw 86 extends through the aperture S2 and engages with retaining shaft 30. Aperture 82 is sufficiently wide to allow middle plate 64 to move freely with respect to lower plate 62, whilst keeping the two plates together. Similarly, a retaining screw 88 passes through aperture 84 and engages with the bore formed in the other end of the retaining shaft 80 to loosely attach the upper plate 66 to the middle plate 64. For aesthetic purposes, the aperture 84 may be covered by a cap (not shown) .

The x, y bearing support 60 enables vibrations of equipment supported on the support to be isolated from the supporting surfaces. The bearing formed between the upper plate 66 and the middle plate 64 isolates the resolved components of vibrations occurring parallel to the y axis from the supporting surfaces, whereas the x-axis resolved components of vibrations are individually isolated by the bearing formed between the middle plate 64 and the lower plate 62. Figs. 8 and 9 illustrate a support 90 according to a further embodiment of the invention, and which is also preferably used in a set. The support 90 operates in generally the same fashion as the linear bearing support 2 previously described. However, the support 90 consists of two opposed metal plates 92 and 94, which are press-formed to produce triangular- section channels 96, 98, 100 and 102 within which two ball-bearings 104 and 106 are constrained. The lower plate 94 is provided with a threaded bore 108 in a central position, and the upper plate 92 has a correspondingly located elongated aperture 110 along which a fixing screw 112 is constrained to move.

Each of the channels 96-102 and the elongated aperture 110 are aligned along the main axis of the support 90. The ball-bearings 104, 106 maintain a gap between the upper and lower plates 92, 94, and the horizontal rolling movement of the ball-bearings within the channels provides for a low-friction vibrational movement of the upper plate 92 with respect to the lower plate 94 only along the main axis of the support 90. Thus, the support 90 may be used in a fashion similar to the manner in which the linear bearing support 2 is used.

The linear bearing support 90 is also provided with lateral support pads 114, 116, 118 and 120, which are adhered to the metal plates adjacent to the triangular channels 96-102. The support pads 114-120 are of a thickness which is approximately equal to the height via which the channels 96-112 protrude from the metal plates 92, 94, such that when electronic equipment is placed on the support 90, the base of the equipment and the supporting surface contact both the tops of the triangular grooves and the pads 114-120 at the upper and lower surfaces of the support 90. However, the pads 114-120 are formed of a slightly compressible material, such that most of the weight of the equipment is supported on the horizontal lines defined by the ridges of the triangular channels 96- 102. This serves to reduce the transmission of vibrations through the support in a manner similar to that of the metal rod 30 described in relation to the linear bearing support 2.

Figs. 10 to 12 illustrate a support 122 in accordance with a further embodiment of the invention, also preferably used in a set. The support 122 is generally similar to the x, y bearing support 60 described in relation to Figs. 5 to 7, except modified in a similar manner to the support 90 described in relation to Figs. 3 and 9. Thus, the x, y bearing support 122 has upper, middle and lower thin metal plates 124, 126, 128 in which triangular bearing grooves are formed by pressing, but which are otherwise generally similar to plates 62, 64 and 66 of the x, y bearing 60. The x, y bearing support 122 is also provided with support pads 130, 132, 134 and ₁3₆ which are essentially similar to the support pads 1₁4- 120 of the embodiment described in relation to Figs. 8 and 9.

The reader will appreciate the operation and advantages of this last described embodiment by considering the description of the relevant features of the embodiments described in relation to Figs. 5 to 7 and 8 and 9, respectively.

When any of the embodiments of support of the present invention are utilised in sets for mounting loudspeakers in the manner described above, superb fidelity of reproduction is obtainable.

For audio equipment other than loudspeakers, such as turntables which have rotational movement, the vibrations naturally set up within the equipment during operation may mainly occur in various horizontal directions. In these, and other cases, supports as described which allow low-friction motion in both the x-direction (backwards and forwards) and the y-direction (side to side) could be advantageously utilised. Other equipment which could benefit from the use of supports according to the present invention include record turntables, CD players, televisions, other audio, or audio-visual equipment, and CD-ROM drives and other computing equipment. In fact, any electronic equipment which produces unwanted vibrations, in particular those having small amplitudes and at least audio frequencies, which would otherwise degrade its performance, and which may be transmitted to other equipment, could benefit from the use of supports in accordance with this invention.

It will be appreciated by a person skilled in the art that various modifications and variations could be employed without departing from the spirit or extending the scope of the invention.

Claims

CLAIMS :

1. A method of mounting electronic equipment, said method comprising providing a support comprising a base and an upper supporting portion on which the electronic equipment is mounted, allowing said upper supporting portion to vibrate freely with respect to said base, and limiting said free vibrations substantially within a horizontal plane, thereby isolating horizontal vibrations created in the electronic equipment from the base.

2. A method according to claim 1, comprising limiting said free vibrations substantially within a linear direction.

3. A method according to claim 2, comprising aligning said linear direction with a main direction of vibration of said electronic equipment.

4. A method according to claim 1, comprising providing an intermediate supporting portion between said base and said upper supporting portion, and allowing said intermediate supporting portion to vibrate freely with respect to both said base and said upper supporting portion.

5. A method according to claim 4, comprising limiting said free vibrations of said intermediate supporting portion substantially within a first linear direction with respect to said base and substantially within a second linear direction with respect to said upper supporting portion.

6. A method according to any of claims 1 to 5, wherein said free vibrations have a frequency of at least 20 Hz.

7. A method of mounting a loudspeaker in accordance with claim 6.

8. A method according to any of claims 1 to 7, comprising providing a plurality of said supports.

9. A support for electronic equipment, said support comprising a base and a free-standing upper supporting portion mounted on the base by a ball¬ bearing constrained to roll freely substantially within a horizontal plane, thereby isolating horizontal vibrations created in the electronic equipment from the base.

10. A support according to claim 9, wherein the ball-bearing makes point-like contact between hard surfaces to support the equipment.

11. A support according to claim 9 or 10, wherein the ball-bearing is constrained between the upper supporting portion and the base by guide means or flange means.

12. A support according to claim 9, 10 or 11, the ball-bearing being constrained for support linear movement along one axis only with respect to said base.

13. A support according to any of claims 9 to 12, further comprising an intermediate supporting portion between said base and said upper supporting portion, said intermediate supporting portion being mounted on the base by a first ball-bearing and said upper supporting portion being mounted on the intermediate supporting portion by a second ball- bearing.

14. A support according to claim 13, wherein said first ball-bearing is constrained to roll substantially within a first linear direction and said second ball-bearing is constrained to roll substantially within a second linear direction.

15. Electronic equipment comprising a support according to any of claims 9 to 14.

16. A loudspeaker according to claim 15.

17. A method of supporting electronic equipment, comprising supporting the equipment to provide one or more horizontal degrees of freedom of movement only so that vibrations in said degrees of freedom are substantially not transmitted through the support.