GB2142504A - Microphone - Google Patents

Abstract

The microphone comprises a body (6) including an electrical conductor system connected with the microphone lead leaving through the sleeve (12). The conductor system comprises a jack-plug socket (20) into which a microphone head or acoustic transducer module (4) is removably plugged by manual effort using a jack-plug (50) on the module to establish electrical connection between the module (4) and the conductor system of the body (6). A number of different heads or modules (4) each with a jack-plug can be provided so each may be mounted in turn on the body (6) as desired. <IMAGE>

Description

SPECIFICATION Microphone This invention relates to microphones.

Known microphones comprise a head affixed to a body, said head comprising transducer means to produce electrical signals in response to acoustic signals impinging on the head. A cable leads from the body to a plug which is removably inserted into a socket forming part of a system handling signals from the microphone. That system may be, for example, a public address system, a radio transmission system, or a recording system.

Different types of microphone are known wherein each type : (i) is designed with the intention of producing a desired electrical signal in response to detecting a certain respective range of sound frequencies in a given acoustic environment, and/or (ii) incorporates in its construction a different kind of transducer, for example, the dynamic microphone, condenser microphone, electret microphone, piezo-electric micophone, ribon microphone, carbon granule microphone, or the hot wire microphone.

According to the environment in which the microphone is disposed and the nature of the sound it is desired that the microphone detect, one or more of the different types is/are better than some others.

Though a certain type which gives a poor response in one set of circumstances may have an excellent response in another set. Therefore sound engineers and others who wish to produce satisfactory reproduction of various sound signals under different conditions need a plurality of different types of microphone. Also, in practice, several microphones, which may all be of the same type are often used simultaneously. Thus the sound engineer may need quite a large number of microphones each with its attendant lead, to give him an adequate number of each type from a range of different types. This is costly and can cause storage and transportation problems.Also substituting a first microphone of one type for a second microphone of another type requires unplugging the lead of the first microphone from a socket and possibly removing that microphone from a stand, and plugging into the socket the lead from the second microphone and possibly mounting that second microphone on the stand, which can be time consuming. Because sockets receiving the plugs are often grouped together and microphone leads can look alike, locating which plug to pull when substituting microphones can give rise to error and can also be time consuming.

An object of the invention is to provide a microphone arrangement capable of at least mitigating certain of the aforesaid disadvantages.

According to a first aspect of the invention a microphone arrangement comprises an acoustic transducer module for converting acoustic signals into electrical signals, said module being mounted in position on a body, the body comprising electrical means to receive as input thereto an output of electrical signals from the module initiated by response of the module to acoustic signals impinging on the module, said module being readily manually mountable on the body and being readily manually removable from the body, and the arrangement being such that each time the module is mounted in said position a connection is automatically established by which the electrical signals are transmissable from the module to the electrical means.

According to a second aspect of the invention a microphone arrangement formed according to said first aspect comprises a plurality of said modules such that any said module can be mounted in position on the body in substitution for any other said module.

With such an arrangement two or more transducer modules, which are interchangeable on the body, can be provided. Each module may be adapted so that by itself or when combined with the electrical means of the body, the respective resultant microphone provides a desired response to a respective acoustic environment and/or to a respective sound frequency range, and if desired, each module may comprise a different variety of transducer. Thus using one body to which at any one time any one of a number of different modules can be fitted, a microphone arrangement is provided which is in effect a plurality of different types of microphone.

Therefore when changing from one type of microphone to another, it is merely necessary to change the transducer module. This there is no need to detach the body from any stand to which it may be fitted. Furthermore, any lead connecting the microphone to a socket can also be left alone. In addition, should a microphone head be faulty or damaged one merely has to replace that head and not scrap the body and attendant lead too.

Each module may be mounted on the body and removed therefrom readily by manual action. For example one may be a simple push fit on the other.

In this case an electrical plug and socket connection is suitable, the body being provided with reception socket means and each module being provided with the corresponding plug or pin means. Or the plug means may be on the body and each module formed with socket means. In a preferred version each module has a jack-plug projecting therefrom the jack-plug contacts of the plug being in electrical connection with the transducer in the microphone head, and the body is provided with the corresponding jack-plug socket connected into the electrical means of the body.

As is known in the microphone art the lead extending from the body can have a jack-plug on its free end for plugging into a system for handling the signals from the microphone. Since the body can have a jack-plug socket, the lead and body of the arrangement formed in accordance with the invention can act as an extension lead for the lead of another microphone.

The electrical means in the body can include switch means which can be manually operable externally of the body to switch the microphone on and off. As one or more of the modules may each include a microphone transducer of the kind requiring the provision of a D.C. polarizing voltage, for example a condenser microphone transducer or a carbon granule transducer, the body can be provided with a compartment or other means to receive one or more dry-cell or equivalent removable batteries to provide that voltage. In this instance the switch means may have three positions, a first or off position, a second or on position to bring into circuit the battery means when a module requiring the polarizing voltage is mounted in the body, and a third or other on-position in which the battery is cut out but the microphone is on when the module used requires no polarizing voltage.

Also switch or change means may be provided in the electrical means in the body to act on the electrical means to vary the response of the microphone arrangementwhen a particular said module is mounted on the body. For example the switch or change means may operate on electrical filter means to vary the frequency response of the microphone.

In some cases, for example with a transducer module comprising a dynamic microphone transducer, the transducer may be connected to a stereo or three contact jack plug projecting from the head.

First and second ends of the dynamic coil may be respectively connected to first and second contacts of the stereo jack plug. The second end may also be connected to the third contact of the plug via transformer means in the head. The frequency response of the microphone can be varied according to whether the output signal for the transducer is supplied to the electrical means of the body via the second of third contact. Electrical switch or change means on the body may be provided to select which of those contacts is used to feed the signal into the body's electrical means.

The electrical means of the body may be provided with manually operable means whereby the polar response of the microphone can be varied. For example in the case where a module comprising a condenser transducer is used with a central plate between two diaphragms wherein the D.C. polarizing voltage between the plate and one diaphram is constant, whereas the polarizing d.c. voltage between the two diaphrams is variable by operating said manual means over a voltage range extending to either side of said constant value. Thus the polar response can be varied from omnidirectional to cardioid.

The electrical means of the body may include one or more transformers. Such will be particularly suitable when a module is used requiring a supply of D.C. polarizing voltage from the battery.

In a preferred arrangement the microphone body is modified by the omission of means to receive one or more batteries, and the aforesaid three-position switch means of the body's electrical means is substituted, by a simple two-position on-off switch.

A module having a transducer of the kind requiring the provision of D.C. polarizing voltage, for example a condenser microphone transducer for use with the modified body can be provided with the battery in the module to provide the polarizing voltage. This battery can be small and of the kind for example, used to power electronic circuits of wrist watches and cameras. The arrangement may be such that the polarizing voltage is applied automatically when the module is fitted to the body and application of the voltage tuaomatically interrupted when the module is removed from the body. The electrical means of the body may include filter means to filter out a surge signal when the switch is switched on to prevent operation of the switch producing an audible click in or from the sound reproduction system when the switch is operated.

The invention will now be further described, by way of example, with reference to the accompanying drawings wherein Figure 1 is a fragmentary longitudinal crosssection of a microphone formed according to the invention; Figure 2 is a fragmentary cross-sectional view of another transducer module for the microphone arrangement in Figure 1; Figure 3 is an electrical diagram of electrical means which can be provided in the body of the microphone in Figure 1; Figure 4 shows in diagrammatic form another co-axial cable attached to the electrical means of Figure 3;; Figure 5 is a fragmentary cross-sectional view of a modification of the module in Figure 1,which modification is a preferred form of condenser microphone module, Figure 6 is an electrical diagram of electrical means of a microphone body for use "inter alia" with the module in Figure 5, and Figure 7shows in fragmentary cross-section another transducer module connected to electrical means, shown diagrammatically, of a microphone formed according to the invention.

In the drawings, a microphone body is shown at 2 and a transducer module at 4, which can convert acoustic signals to electrical signals. The body 2 comprises a main body part 6 with an internal cavity 8 from which a passage 10 extends for admitting a co-axial cable (not shown in Figure 1) passing through an end sleeve 12 locked on the body by a set screw 14. Another set screw 15 locks against the insulation of an inner conductor of the cable. At its other end the body part 6 receives a bush 16 locked in place by a set screw 18. This bush mounts a jack-plug socket 20 comprising an inner tubular conductor passage 21 (Figure 3) within a screw threaded part 22 on an element 24 carrying a spring clip conductor 26 forming part of a first electrical conducting path including terminal tag 28. The tubular conductor passage 21 forms part of a second conductor path including terminal tag 30. Both conductor paths are insulated from each other.

The socket 20 is clamped in position on bush 16 between insulating rings 34 and 36 on either side of an inner web 38 on the bush, the clamping pressure being between element 24 and a nut 40 on threaded part 22.

The body part also mounts a three position switch 32 manually operable from outside the body.

The transducer module 4 comprises an inner sleeve shaped housing 44 containing a condenser microphone capsule 46 having an outer wall 48, and a two-contact jack-plug 50 having a cylindrical body 52 is disposed so that its first and second contacts are in electrical connection with respective electrical parts of the capsule.

Essentially the module 4 forms the head of the microphone. If desired, the module can be provided with a cover over the capsule 46, for example a unisphere cover 42, which may be removable.

When the module 4 is mounted in the body 6 a first contact 54 of the jack-plug contacts the conducting sleeve 21 of the socket whereas the other or second contact 56 (insulated by ring 58 from contact 54) contacts the spring 26.

Body part 6 contains a compartment 60 to receive one or more dry cell batteries 62 (Figure 3) to provide polarizing D.C. voltage for the condenser microphone module 4.

The body part 6 contains an electrical circuit system (shown in Figure 3) in which conductors 21 and 26 are connected to a primary coil 64 of a transformer 66 having a secondary coil 68. The switch 32 has two switch contacts 70, 72. In a first position of the switch both contacts are open and the microphone is off. In a second position both contacts 70,72 are closed so that a polarizing voltage from battery 62 can be applied to condenser module 4 and output signals therefrom are applied to transformer 66.

Secondary coil 68 is connected to a coaxial cable 74 entering the body part 6 through the sleeve 12. In this case the cable is unbalanced, 76 being its outer sheath conductor and 78 its inner conductor. In Figure 4 coaxial cable 74A is balanced by reason of outer ends of the secondary coil 68 being respectively connected to respective inner conductors 76A, 76B of the coaxial cable 74A having an outer conducting sheath 76A connected to a centre tapping of coil 68.

In Figure 2 an alternative transducer module 4A is shown which can be mounted on the body 2. This module comprises an inner sleeve shaped housing 44A containing in dynamic microphone capsule 46A connected electrically to a projecting jack-plug 50A.

When module 4A is mounted on body 2 in place of head 4, the switch 32 is moved to its third position to switch on the microphone. In that state contact 70 is closed but contact 72 is open.

A preferred modification of the transducer module of Figure 1 is shown at 4B in Figure 5. The module 4B comprises a condenser micro-phone capsule 46B in sleeve 44B which is recessed and contains a small battery 80 which may be readily replaceable. The sleeve is mounted in a body 82 on which jack plug 50B is mounted. As shown in Figure 6 one plate 84 of condenser transducer is electrically connected with the positive terminal of battery 80. The other plate 86 of the transducer is connected by line 87 to contact 54B of the jack-plug. The other contact 56B of the jack-plug is connected to the negative terminal of battery 80 by a conducting path insulated from contact 54B.

For use in conjunction with the module 4B, the electrical means of the microphone body includes conductor passage 21 B of jack-plug socket on the body, a spring clip conductor 26B, a transformer 66, a two position on-off switch 88, a condenser 90 and a resistor 92. When the module 4B is fitted to the jack-plug socket as shown in Figure 6, condenser plate 86 is automatically connected to the negative terminal of battery 80 via a conducting path established between jack-plug contact 56B and conductor 268 and including resistance 92, conductor 21 B, jack plug contact 54B and line 87. Therefore the condenser transducer is subjected to polarising voltage of the battery 80.

The combination of resistor 92 and condenser 90 forms a filter. When the microphone is switched on by closing switch 88, the filter prevents the microphone arrangement giving an output to cable 74 which could produce an audible click or crackle from the sound reproduction system to which the cable is attached.

It will be appreciated that when the electrical circiut of Figure 6 is used, the body 2 in Figure 1 is modified by at least the omission of the battery compartment 60 and the substitution of switch 88 for the switch 32.

If desired transformer 66 can be omitted and the connection to cable 74 be as shown by dotted lines X and Y.

It will also be appreciated that module 4A can also be plugged into the circuit of Figure 6 instead of module 4B.

A plurality of modules provided for mounting on the microphone body can each be arranged for example by electrical or electronic adaption, to have a different respective acoustic frequency response.

For example one may be adapted to give an electrical output corresponding to a wide range of acoustic frequencies, another adapted to give an electrical output corresponding to the more high acoustic frequencies, and may substantially cut-out lower frequencies, another adapted to give an output corresponding to lower acoustic frequencies and may substantially cut out higher frequencies another being adapted for particular response to the frequencies of the human voice, and another more suited to respond to music which may be made by one or more instruments. The transducers of such modules may all be of the same variety, for example dynamic microphone transducers or two or more different varieties of tranducer may be used each module comprising a given transducer.

If desired, the jack-plug and socket used may be a stereo jack plug and socket arrangement in which the jack plug has three contacts. Such an arrangement is shown in Figure 7 applied to a dynamic microphone transducer module 4C provided with a stereo jack plug 50C having three contacts 54', 54C and 56C separated by insulating rings 58' and 58C. In this case the socket on the microphone body comprises conductor passages 21 21C and spring clip conductor 26C which connected to the electrical circuit in the microphone body comprising three possition switch 32C and are arranged to make contact with the plug contacts 54', 54C and 56C respectively when the plug is home in the socket.

The module is electrically adapted internally for giving two different output responses. One response is available from the module when contacts 54', and 56C are in circuit, and the other is available when contacts 54C and 56C are in circuit. Therefore either response can be selectively input to the electrical means in the microphone body according to whetherthe switch 32C is made through switch contact 94 or 96.

Claims (13)

1. A microphone arrangement comprising an acoustic transducer module for converting acoustic signals into electrical signals, said module being mounted in position on a body, the body comprising electrical means to receive as input thereto an output of electrical signals from the module initiated by response of the module to acoustic signals impinging on the module, said module being readily manually mountable on the body and being readily manually removable from the body, and the arrangement being such that each time the module is mounted in said position a connection is automatically established by which the electrical signals are transmissable from the module to the electrical means.

2. A microphone arrangement as claimed in Claim 1, comprising a plurality of said modules such that any said module can be mounted in position on the body in substitution for any other.

3. A microphone arrangement as claimed in Claim 1 or Claim 2, in which the or each module is mounted on the body using a plug and socket connection.

4. A microphone arrangement as claimed in Claim 3, in which the plug and socket connection is a jack-plug and socket.

A microphone arrangement as claimed in Claim 4, in which the jack-plug is a stereo or three contacttype jack plug.

6. A microphone arrangement as claimed in Claim 2 or any one of Claims 3 to 5 when appended to Claim 2, in which there are at least two said modules and at least one has to acoustic signals a different response to another said module.

7. A microphone arrangement as claimed in Claim 6, in which at least one said module has a different acoustic frequency response to another said module.

8. A microphone arrangement as claimed in any one preceding claim comprising filter means for surpressing in the electrical means, electrical signals which correspond to a click at switch-on of the microphone arrangement.

9. A microphone arrangement as claimed in Claim 2 or any one of Claim 3 to 7 when appended to Claim 2, in which the electrical means comprises different circuit paths each corresponding to a different said module, and electrical switch means for selectively bringing into circuit a particular said path corresponding to the module mounted orto be mounted on the body.

10. A microphone arrangement as claimed in any one preceding claim in which the electrical means comprises battery means to provide polarising voltage from a said module comprising a condensor microphone transducer.

11. A microphone arrangement as claimed in any one of claims 1 to 10, in which the or a said module comprises a condensor microphone tranducer, and further comprises battery means to provide polarising voltage for the transducer.

12. A microphone arrangement as claimed in Claim 11, so arranged that the polarising voltage is automatically applied to the transducer by the act of mounting the module on the body.

13. A microphone arrangement substantially as hereinbefore described with reference to the accompanying drawings.