Abstract:
A transducer assembly may include a first transducer having a first front volume, a first back volume and a first port acoustically coupled to the first front volume; and a second transducer having a second front volume, a second back volume and second port acoustically coupled to the second front volume. The first front volume and the second front volume are acoustically coupled to increase the effective back volume of both the first transducer and the second transducer. An optional signal processing circuit may be used to control the output of the first transducer based upon a signal received from the second transducer.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This patent claims benefit under 35 U.S.C. § 119(e) to U.S. Provisional application Ser. No. 60/679,170, filed May 9, 2005 and entitled Conjoined Receiver and Microphone Assembly, the disclosure of which is hereby expressly incorporated herein for all purposes. 
     
    
     TECHNICAL FIELD  
       [0002]     This patent generally relates to miniature transducers used in listening devices and portable communication devices, and more particularly, to a conjoined receiver and microphone.  
       BACKGROUND  
       [0003]     A common problem with listening devices and portable communication devices is to avoid exceeding the discomfort threshold in the sound signal and to maintain a constant sound pressure level (SPL) to the listener. In order to simplify the operation of the devices, SPL can be maintained by signal amplitude regulation with a feedback structure. In such an arrangement, the amplifier input signal is fed to a level detector. The level detector output value is delivered to a control loop providing attenuation of the amplifier output signal at increasing input signal strength. However, such compensation is not capable of satisfactorily eliminating the excessive SPL to prevent potential long term damage to hearing characteristics of a person. Further, to improve the receiver efficiency, more power will be drawn from the power source, i.e. battery, to increase output. However, draining the energy from the battery may cause power supply voltage fluctuating and reduced battery life. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]     For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawings wherein:  
         [0005]      FIG. 1  is cross-sectional view of a conjoined receiver and microphone assembly;  
         [0006]      FIG. 2  is a perspective view of the conjoined received and microphone assembly of  FIG. 1 ;  
         [0007]      FIG. 3  is a schematic representation of a conjoined receiver and microphone assembly and a signal processing circuit;  
         [0008]      FIG. 4  is a schematic representation of a conjoined receiver and microphone assembly without a signal processing circuit; and  
         [0009]      FIG. 5  is a graph indicating output sound pressure level with frequency response. 
     
    
     DETAILED DESCRIPTION  
       [0010]     While the present disclosure is susceptible to various modifications and alternative forms, certain embodiments are shown by way of example in the drawings and these embodiments will be described in detail herein. It will be understood, however, that this disclosure is not intended to limit the invention to the particular forms described, but to the contrary, the invention is intended to cover all modifications, alternatives, and equivalents falling within the spirit and scope of the invention defined by the appended claims.  
         [0011]     It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______ ’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning. Unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. § 112, sixth paragraph.  
         [0012]      FIGS. 1-2  illustrate an exemplary embodiment of a conjoined receiver and microphone assembly  100  for use in virtually any type of device, such as cellular phones, web-enabled cellular telephones, Personal Digital Assistants (PDAs), hand-held computers, Bluetooth wireless headset, digital cameras, other types of portable computing and Internet access appliances and devices, hearings aids, in-ear monitors, electronic hearing protection devices, and the like. The assembly  100  includes a a first transducer, e.g., microphone  200  and a second transducer, e.g., receiver  300  mounted in back-to-back abutting relation to provide a shared volume. The shared volume is larger than is available in discrete devices and acts to increase the efficiency of the receiver  300  at low frequency response. In alternate embodiments, the microphone  200  and the receiver  300  can be mounted in front-to-front alignment to again provide a shared volume. Alternatively, the first and second transducer can both be receivers sharing a volume to enhance low frequency response and efficiency or can both be microphones enjoying the same benefits provided by the shared volume. A dual receiver arrangement is shown and described in commonly assigned U.S. patent application Ser. No. __/______, entitled ______, the disclosure of which is hereby expressly incorporated herein for all purposes.  
         [0013]     The microphone  200  includes a front inlet port  202  communicating with a front volume  204  and a back inlet port  206  communicating with a back volume  208 . The receiver  300  has a sound outlet tube  3   10  for transmission of an acoustic signal to a user and includes a front inlet port  302  communicating with a front volume  304  and a back inlet port  306  communicating with a back volume  308 . The back inlet ports  206  of the microphone  200  and the back inlet port  306  of the receiver  300  are aligned and joined such that the back volume  208  of the microphone  200  and the back volume  308  of the receiver  300  form a single back volume, i.e., a shared volume. The increased back volume of the combined volumes  208  and  308  results in an increased efficiency of the acoustic output of the receiver  300 , especially at low frequency. This configuration further eliminates a need for an additional sound tube that would otherwise be necessary to couple to the back volume  208  of the microphone  200 .  
         [0014]      FIG. 3  illustrates a conjoined assembly  100  adapted with a signal processing circuit  400 . The conjoined assembly  100  and the signal processing circuit  400  provide for monitoring and controlling the acoustic output sound pressure level (SPL) in an ear canal. However, the conjoined assembly  100  may be used to achieve the same effects in devices not disposed directly into the ear canal. A sound signal within the ear canal entering the microphone  200  is converted to an electrical signal before transmission to the receiver  300 . The control signal processing circuit  400  connected between the microphone  200  and the receiver  300  operates to generate a control signal responsive to the microphone  200  output signal. The receiver  300  is responsive to the microphone  200  output signal and the control signal such that oversensitivity of the assembly  100  in the form of excessive SPL is prevented. The receiver  300  thus receives and converts the controlled electrical signal to a sound signal for transmission to the user. The control signal processing circuit  400  may includes a control signal circuit, a converter, a SPL adjusting circuit, and/or a digital signal Processor (DSP).  
         [0015]     Separate power sources may be provide for each of the conjoined assembly  100  and the signal processing circuit  400 , which may enhance noise isolation. Furthermore, the signal processing circuit  400  may not be disposed within the housing of the conjoined assembly  100 , but instead may have a separate housing and may be communicatively linked, for example by wired or wireless connection, to the conjoined assembly  100 .  
         [0016]      FIG. 4  illustrates a conjoined assembly  100  without a signal processing circuit. The conjoined assembly  100  is still operable for monitoring and controlling the acoustic output sound pressure level (SPL) in an ear canal. In this embodiment, the microphone  200  is arranged to receive the sound signal generated by the receiver  300 , which is used to monitor and limit the SPL of the sound signal delivered from the receiver  300  to the ear canal.  
         [0017]      FIG. 5  illustrates a graphical representation indicating output sound pressure level with frequency response. Back volume coupling the microphone  200  to the receiver  300  preserves more bandwidth of the receiver. When back volume coupling the microphone  200  to the receiver  300 , the second peak becomes more damped. In an alternate embodiment, when the microphone  200  and the receiver  300  front-to-front alignment, a higher peak level, i.e. about 3 dB is provided from the receiver  300 .  
         [0018]     All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extend as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.  
         [0019]     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.  
         [0020]     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.