GB2202409A

GB2202409A - Microphone mount

Info

Publication number: GB2202409A
Application number: GB08806335A
Authority: GB
Inventors: Carl R Anderson; Leonard A Morrison
Original assignee: Shure Brothers Inc
Current assignee: Shure Inc
Priority date: 1987-03-19
Filing date: 1988-03-17
Publication date: 1988-09-21
Also published as: FR2612717A1; JPS63254893A; DE3808055A1; GB8806335D0

Description

2r4,2409 1 A MICROPHONE MOUNT FOR USE WITH AN AUTOMOBILE COMMUNICATION

SYSTEM This invention relates to a microphone system mounted for use in an automobile. More particularly, this invention relates to an improved microphone and microphone mounting construction for hands-free use in an automobile communication system such as a mobile cellular telephone.

Portable telephones used in automobiles have become commonplace, especially with the advent of cellular telephone systems throughout the United States. Typically, such automobile telephone systems use handsets containing both the telephone's speaker and microphone and configured much like a conventional telephone handset. Although conventional handsets are effective and useful, they require the automobile operator to entirely dedicate one hand to operation of the telephone, leaving only the remaining hand to operate the vehicle. This situation naturally leads to substantial safety concerns and presentsproblems of awkwardness and difficulty of use when a driver attempts to operate the mobile telephone while, for example, turning a corner or parking the automobile. These problems are especially prevalent in standard transmission vehicles, where the driver and telephone user frequently must use one hand to control the steering wheel and the other to operate the gear-shift mechanism.

Hands-free operation of the cellular communication system requires that the microphone be positioned at a location other than a handset, which necessarily implies 2 that the microphone will be at a greater distance from the speaker's mouth. However, moving the microphone away from the immediate vicinity of the mouth leads to significant problems with background noises. Thus, the principal acoustic problem confronting the designer of a hands-free microphone system is the need to maintain a high signalto-noise ratio.

The noise level in a vehicle varies between particular vehicles and the operating conditions of that vehicle. For example, the vehicle's speed, the road surface travelled and the accessories operating within the vehicles (such as an air conditioner and blower, or the vehicle's radio) can all add to the principal background noises: wind and motor sounds. Generally, the microphone must be designed for use in a high noise environment. Although the noise level varies slightly at different locations in a moving vehicle, it is almost always sufficient to cause significant deterioration of the sound pick-up when microphones are placed at a substantial distance from the user's mouth. For the purposes of designing a vehicle microphone, the noise level can be reasonably approximated as uniform throughout the vehicle.

The problem of hands free use then becomes maintaining a high signal-tonoise ratio for a microphone positioned away from the speaker's mouth. A logical location for such a microphone is the automobile steering wheel; in most vehicles that location is approximately 16 or more inches away from the driver's mouth. Since the 4 1 3 direct sound pressure resulting from a speaker's voice is inversely proportional to the distance from the mouth to the microphone, a microphone mounted approximately 16 inches from the mouth has only 1/16 of the sound pressure available to a microphone in a telephone handset positioned approximately 1 inch from the mouth. A 16 inch distance therefore results in an approximate 24 decibel reduction in signal strength; a 24 decibel reduction may easily produce an unacceptable signal-to-noise ratio.

Alternative arrangements for locating a microphone are workable but generally inefficient. While the problem can be alleviated somewhat by using directional microphones, the situation remains essentially a problem of reducing the distance from the microphone to the speaker's mouth. These problems can usually be avoided by using a "boom" microphone mounted on a headset, and such headsets have been constructed and used in the prior art. However, boom microphone and headsets arrangements produce substantial user resistance and are generally without adequate marketability.

Alternative arrangements attempted in the prior art less effective than either using a boom microphone or mounting the microphone on the steering wheel. For example, microphones mounted on the automobile's visor are also at least 16 inches or more from the users mouth, with a consequent unacceptable reduction in sound quality. Additionally, the visor location is extremely sensitive to wind noise, especially noise produced by drafts from an air conditioner blower or from an open window. Moreover,

4 the visor location is not ideal, since an automobile driver's voice is usually directed generally in a more downward direction. Dashboard microphones are located more in the direction of the speaker's voice, but are even further from the driver's mouth than steering wheel microphones. Window or similar locations produce many of the same difficulties. In short, any microphone location that is more than approximately 6 inches from the mouth is likely to result in an undesirable signal-to-noise ratio.

According to the present invention a microphone mount for use in an automobile communication system comprises a mounting element having means for receiving a microphone, and means for attaching the mounting element to an automobile restraint belt. The attaching means preferably allows slideable attachment to enable the position of the mounting element on the belt to be adjusted, but provision may also be made for preventing undesirable sliding on the belt. In a preferred embodiment, the mounting element comprises a base and at least one set of opposed fingers attached to and extending across the base and defining a belt retention zone between the fingers and the base.

Microphone mounts of this invention can be easy to use and allow the vehicle operator to have both hands free to control the vehicle. At the same time though, the "hands free" microphone and microphone mount may be positioned no more than approximately 6 inches from the user's mouth without interfering with the control of the vehicle.

Microphones and microphone mounts of the invention 1 1 can produce a high signal-to-noise ratio. Thus, they can be used in a vehicle communication system that has little tendency to be adversely affected by wind, background or accessory noises of a motor vehicle. Neither need they interfere with the mechanics of operating an automobile, such as the gear shift, steering wheel, or safety restraint system, and their effective mounting on the user's body results in them being substantially protected from mechanical vibration of the vehicle.

Preferred embodiments of the invention are easily adjustable for use by a variety of different persons in variety of different vehicles. They can be used with a conventional directional microphone, and may be compact and unobtrusive.

As noted above, the means'for attaching the mounting element to a shoulder belt preferably allows sliding movement of the microphone and mount to any position along the belt. In the preferred embodiment, the mount is used on the shoulder portion of a seat belt restraint system. Also in preferred embodiments. the microphone cord is adapted to extend either from the microphone cover along the shoulder belt to the retractor on the automobile's door post, or, in vehicles having automatic shoulder belt retractors, along the belt to its terminator on the seat. The preferred embodiment is further adapted to position a directional microphone for optional signal-to-noise ratio when used in the vicinity of a vehicle driver's collarbone.

6 Some preferred embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, wherein like numerals refer to like elements, and in which Figure 1 is a perspective view of one embodiments of the invention mounted on an automobile shoulder belt and used in an automobile; Figure 2 is an exploded perspective view of the embodiment of Figure 1 illustrating the assembly of the elements of the mount; Figure 3 is a top plan view of the interior of the microphone mount in Figure 2, shown with the cover removed; Figure 4 is a bottom view of the microphone mount cover of Figure 2; Figure 5 is a bottom view of the microphone mount cover of Figure 2, and showing a wind screen inserted in the cover; Figure 6 is a side view of the upper mount structure of the embodiment of Figure 2; Figure 7 is a front view of the upper mount structure illustrated in Figure 6.; Figure 8 is a top view of the upper mount structure illustrated in Figure 6; Figure 9 is a top view of the lower mount structure, illustrating the arrangement for sliding the microphone mount on an automobile shoulder belt; Figure 10 is a side view of the structure illustrated in Figure 9; 7 Figure 11 is a front view of the structure illustrated in Figure 9; Figure 12 it a perspective view of an alternative embodiment of the invention, showing the microphone and microphone mount configured for use on an automatically retracting shoulder belt; Figure 13 is a bottom perspective view of the embodiment of Figure 12 illustrating the structure that prevents sliding along the belt; Figure 14 is an illustration of the polar response curve for the preferred embodiment, measured at 1000 Hertz; Figure 15 is a perspective view of another alternative embodiment of the invention, shown in use; Figure 16 is a top perspective view of the embodiment illustrated in Figure 14; and Figure 17 is a side view of the embodiment illustrated in Figure 14.

1 The preferred embodiment of this invention is a microphone and microphone mount adapted for use in an automobile communications system such as cellular mobile telephone. The microphone and mount are adapted to be slideably attached to the driver's shoulder belt of a conventional automobile restraint system. The microphone and mount are adapted to be used when in the approximate location of the driver's collarbone.

The preferred embodiment of the invention is illustrated in Figure 1. An assembly 10 is mounted on a a shoulder restraint belt 12 of a vehicle 13. The assembly is preferably positioned along the belt 12 in the vicinity of the collarbone of the motor vehicle operator, thereby allowing the system to be used in a near optimum location for receiving sound and minimizing background noise. A coiled communications cord 14 connects the assembly 10 to the communications system by attachment to the door post 16 of the automobile. An uncoiled segment 17 of the communication cord follows the door post molding to the main electronics of the cellular telephone system. The assembly 10 is loosely slideable on the belt 12, and is positioned by fastening the length of cord to an anchorage (not shown) on the door post.

The details of this embodiment of the invention are best illustrated in Figures 2 to 11. Referring particularly to Figure 2, the assembly 10 comprises a lower base 18, an upper base 20 and a cover 22. A microphone cartridge 24 is attached in the lower base 18. In the preferred embodiment, a 6 mm (0.235 inch) diameter cardioid electrode capacitor microphone cartridge is used.

As best illustrated in Figures 2, 3 and 9-11, the lower base is configured.to accept the microphone cartridge 24. The lower base includes a mounting platform 26, supported by two ends 28. To receive the microphone cartridge, the mounting platform 26 includes a recess 30. In the preferred embodiment. the recess is rectangular, although other configurations are also appropriate, so long as they are of a size capable of receiving the microphone cartridge 24.

9 To hold the microphone cartridge 24 in the recess 30, the recess includes opposed support flanges 32 extending out of the recess. The microphone cartridge 24 is secured between the support flanges 32 by the tension of a surrounding foam block 31. In an alternative embodiment, the cartridge is secured between the support flanges by two segments of foam blocks 34, preferably made of segments of doublestick adhesive foam.

For ease of manufacturing, the base is made of two parts. Thus, the upper base 20 is mateable with the lower base 18. Preferably, the lower base has end flanges 36 extending from the ends 28 of the lower base. The upper base in turn has ends 38 that align with the end flanges 36. The upper base 20 also includes an opening 40 that corresponds in size and shape to a rim 42 in the lower base extending around the recess 30. When the upper and lower bases are assembled, the rim 42 extends into the opening 40 allowing access to the microphone cartridge 24.

The upper base 20 and lower base 18, when configured together, also provide an arrangement for sliding movement of the assembly 10 on a shoulder restraint belt. Thus, the preferred embodiment of the lower base includes 4 fingers 44 extending inwardly from the.lower base ends 28. As best illustrated in Figure 6, the upper base 20 has twin contact surfaces 46, and the lower base 18 has corresponding lower contact surface 48. When the upper and lower bases are assembled as a unit, the contact surfaces 46 and 48 provide a sliding surface for the k 1 shoulder belt. The remaining surface contacting the shoulder belt is the upper side of the fingers 44. The use of fingers 44 allows easy placement of the assembly 10 into a shoulder belt simply by bending the shoulder belt with a longitudinal crease to fit underneath the fingers 44. To reduce material usage and increase the bending strength of the lower base, the lower base includes lower recesses 50. The lower recesses are preferably formed during the molding process when both base units are made, usually of a plastic material.

As best illustrated in Figures 2 and 3, the microphone cartridge includes a cord 52 leading from the cartridge to the exterior of the assembly 10. The upper base assembly 20 is configured to include a structure for securing the cord 52 in the assembly forming a strain relief to prevent damage to the cartridge when the assembly cord is stressed. In the preferred embodiment, the microphone cartridge 24 includes lead wires 54. Those lead wires are attached to a connection board 56 which in turn is electrically connected to cord 52. Although the connection board 56 can be affixed to the upper base 20, in the preferred embodiment the connection board merely rests on the upper base and is primarily held in place by attachment ot the cord 52. The upper base 20 includes twin tie posts 58.

As best illustrated in Figures 2 and 4, the assembly includes a cover 22 having opening slots 60 to allow sound to enter into the assembly's interior. In the preferred embodiment, the slots are positioned at a slant to the c.

longitudinal axis of the microphone cartridge 24. With the microphone positioned with the slanted slots as illustrated-in Figure 1,, the normal directional character of the microphone cartridge is then biased slightly more toward the mouth of the user.

In the preferred embodiment, the slots are positioned at an approximate 450 angle to the longitudinal axis of the microphone cartridge 24. As illustrated by figure 14, the resulting polar pattern 62 for the directional microphone cartridge 24 is then offset approximately 150 of rotation toward the slots. The polar pattern illustrated in Figure 14 is measured at 1000 Hertz. It represents an approximate polar pattern for frequencies between approximately 300 and 2,000 Hertz. The line between the 0 and 180 degree markings represents the axis of the microphone cartridge 24.

The assembly 10 also includes a wind screen 62 inserted within the cover 22. The wind screen is preferably of a non-woven fabric material that is substantial permeable to sound but still has wind screening ability. Although a conventional rubber foam can be used, the preferred embodiment uses a much thinner material known as viskon. Alternatively, the wind screen can be constructed of cloth.

The interior of the cover 22, as best illustrated in Figures 4 and 5, includes a grounding lug 66 and a part of bolt bosses 68. In the preferred embodiment, the bosses are threaded to receive bolts 70. The bosses 68 are configured to correspond to bolt holes 72 in the lower 12 base 18 and 74 in the upper base 20. To provide a flush surface 48, the bolt holes 72 in the lower base 18 are provided with a countersink 76. to allow room for the grounding lug and bolts, the wind screen 64 is cut in a pattern covering only a portion of the cover 22; any pattern is appropriate so long as the wind screen fully covers the opening slots 60.

The assembly 10 also includes an acoustic damper 78. The acoustic damper is preferably made of felt and is configured with a microphone opening 80 allowing the mounting platform 16 of the lower base assembly to be exposed through the acoustic damper. The acoustic damper 78 occupies the space under the cover not accessed by slots 60 and provides additional retention for the lead wires 54, connection board 56, and cord 52. It also prevents movements of those elements within the assembly after the bolts 70 have been fully connected.

The cover 22 in the assembly also includes a recess 82 suitable for placement of a logo tag or the like. In the preferred embodiment, the recess extends below the surface on the upper side of the cover 22.

As illustrated in Figures 4 and 5, the cover 22 includes two cord openings 84 on opposite side of the cover. The upper base 20 has a corresponding plug 86 matching the size and shape of one of the cord openings. The use of dual cord openings, when combined with an upper base 20 that is separate from the lower base, allows the cord 52 to extend from either side of the assembly merely by turning the upper base assembly 1800.and allowing the 1 13 cord to extend from the other side. In either position, the plug 86 fills the unused cord opening 84.

Referring now to Figure 12, the general concept of the invention is further illustrated along with an alternative installation procedure. In Figure 12, an automobile vehicle having a retractable shoulder belt 88 is illustrated. That shoulder belt connects to a shuttle 90 mounted in slot 92 extending from the approximate front of the driver's side window to the top of the doorpost molding 94. In vehicles having a retractable shoulder belt, engine shut down results in operation of a mechanism (not shown) that automatically moves the shuttle 90 forward in the slot 92 and thereby disengages the occupant from the shoulder belt. The seat belt 96 is releasably secured with a buckle (not shown) on the driver's side.

To allow the assembly 10 to be used with an automatically retracting shoulder belt system as illustrated in Figure 12, the assembly must be adapted to have the cord 52 connect at some position other than the top of the doorpost molding 94. When retractable shoulder belts are used, the assembly 10 is configured with the cord 52 exiting from the opposite side of the cover 22 from that shown in Figure 1, as discussed above. The cord then extends downwardly along the shoulder belt and connects to the lap belt near the seat, between the driver and passenger positions. An uncoiled portion 98 of the cord then extends to an electronics cabinet 100. The electronics cabinet includes all of the necessary components to interface the microphone cartridge 24 with a 14 conventional cellular telephone system. The electronics cabinet 100, in either the embodiments of Figure 1 or 12, is mounted anywhere within the vehicle that is convenient; for cosmetic purposes, the electronics cabinet 100 is conveniently mounted out of view underneath the dash.

In the embodiment of Figure 1, (combined shoulder and lap belt) the assembly 10 is intended to slide along the shoulder belt 12. Thus, when the belt is retracted, the seat clip of the assembly of Figure 1 (not shown) comes in contact with the microphone. The belt then slides between the finger 44 and the contact surface 46 and the microphone is positioned between the seat clip and the belt anchorage on the door post. When the user initially enters the car, he merely grasps the clip, moves it to pull the belt'across his lap and chest, and snaps it into the receptacle in the seat corner. Friction and gravity will cause the microphone to descend, and tension of the coiled cord will position the microphone as shown.

In the embodiment of Figure 12. the shoulder belt is never retracted and the assembly is then adapted to prevent its movement along belt. As best illustrated in Figure 13, such movement is prevented by use of a key 102 slipped between the belt 88 and the contact surface 46. In the preferred embodiment, the key is constructed of a plastic material of the same type is that used for the upper and lower base. However, any material that restricts sliding of the belt 88 may be employed.

The embodiment of Figures 1-13 may also be prepared in a "mirror image" structure, having the same features A 1 but with all positions reversed. In such a configuration, the embodiment may be appropriately used in.a right hand drive vehicle, such as a postal vehicle or vehicles that are used in various foreign countries like the United Kingdom.

Referring now to Figures 15-17, an alternative embodiment of the invention is disclosed using a removable microphone. In the alternative embodiment, a second assembly 104 is attached to a shoulder restraint belt system in generally the same position with respect ot the user as assembly 10.

Just as in the embodiment of assembly 10, electrical communication between the assembly and the electronics cabinet (not shown) occurs through a cord connected to the door post molding 16. However, in the embodiment disclosed in Figure 15, the communication is accomplished through a conventional coiled cord 106. The embodiment of the second assembly can also use a coiled cord, similar to that disclosed as part of the preferred embodiment.

As illustrated most clearly in Figures 15-17, the second assembly 104 comprises an upper base 108 and a lower base 110 clamped about the shoulder restraint belt 12. A conventional microphone 112 is removably attached to the upper base 1 108 through a mounting clamp 114. The mounting clamp can be of any configuration suitable for removably holding a microphone; in the embodiment of Figures 15-17, the mounting is of the kind disclosed in U.S. Patent No. 4,577,070. Alternatively, the mounting clamp 114 can be of a kind that permanently attaches to 4 4, 16 microphone.

The embodiment of Figures 15-17 also includes a clamping mechanism for attaching the upper base 108 and the lower base 110 about the restraint belt 12. Such a mechanism preferably comprises bolts 116 attached through lower base 110 into threaded openings 118 in upper base 108. The upper and lower bases are then clamped about the restraint belt 12, providing a friction fit with that belt and preventing the assembly 104 from sliding along the belt.

Although the embodiment of Figures 15 to 17 provides mountings that are positioned by hand along the shoulder belt, alternative embodiments of the invention can be constructed incorporating the system previously described for retraction and deployment of the shoulder belt. The mechanism can also be adapted to position the microphone at a position approximating the centre of the occupants chest (the position shown in Figure 15) when the shoulder belt is strapped in place by the occupant, thereby ensuring that the microphone is relatively close to an ideal location.

As disclosed in Figure 16, the position of the microphone 112 is preferably such that the microphone points toward the mouth of the user. In that manner. a directional microphone can be used that minimizes interfering noise from the multiple sources of sound present in any moving vehicle.

While the three embodiments of the present invention specifically described above use of the assembly by the 1 1 1 1 17 automobile driver, the invention may be used by any occupant of the vehicle by attaching the microphone mount to the respective restraint belt and providing the requisite electrical connection points.

i k 1 E3

Claims

CLAIMS: 1. A microphone mount for use with an automobile communication

system comprising a mounting element having means for receiving a microphone, and means for attaching the mounting element to an automobile restraint belt.
2. A microphone mount according to Claim 1 wherein the attaching means allows slideable attachment to enable the position of the mounting element on the belt to be adjusted.
3. A microphone mount according to Claim 1 or Claim 2 wherein the mounting element comprises a base and at least one set of opposed fingers attached to and extending across the base and defining a belt retention zone between the fingers and the base.
4. A microphone mount according to Claim 2 or Claim 3 wherein the mounting element includes means for preventing the element from sliding on the belt.
5. A microphone mount according to any preceding Claim including a wind screen for covering a microphone received on the mount.
6. A microphone mount according to any preceding Claim including a cover for a microphone received on the mount.
7. A microphone mount according to Claim 6 wherein the cover has at least one opening to allow sound to propagate to a said microphone.
8. A microphone mount according to Claim 7 wherein said at least one opening is configured to directionally bias reception of sound.
9. A microphone mount according to Claim 8 wherein said

1 j lq at least one opening comprises at least one slot in the cover.
10. A microphone mount according to any precedingClaim with a microphone received thereon.
11. A microphone mount according to.Claim 10 wherein the microphone includes a case which is an integral part of the mount.
12. A microphone mount according to Claim 10 wherein the microphone is removably received on the mount.
13. A microphone mount according to any of Claims 10 to 12 including a cord for extending from the microphone to a fixture in a said automobile.
14. A microphone mount according to Claim 13 including means attached to the cord for securing the cord at a said fixture.
15. A microphone mount according to any of Claims 10 to 14 wherein the microphone is a directional microphone.
16. A microphone mount according to claim 8 or claim 9 and Claim 15 wherein said at least one opening is configured to direct sound towards the microphone.
17. A microphone mount substantially as described herein with reference to the accompanying drawings.
18. The combination of an automobile restraint belt and a microphone mount according to any preceding Claim attached thereto.
19. A combination according to Claim 16 wherein the belt is a shoulder restraint belt.
20. A combination of an automobile restraint belt and a microphone mount substantially as described herein with 42-0 reference to the accompanying drawings.
21. An automobile fitted with a combination according to any of Claims 18 to 20.
22. An automobile according to Claim 21 including a mount according to Claim 13 wherein the cord extends to a door post molding of the automobile.
23. An automobile according to Claim 21 including a mount according to Claim 13 wherein the cord extends to the restraint belt mounting at a seat of the automobile.

Published 1988 at The Patent Office, State House, 66171 High Holborn, London WC1R 4TP. Further copies may be obtained &om The Patent Office, 1 7 1