Abstract:
An in-ear headphone with sound pick-up capability is disclosed. The in-ear headphone includes a pair of ear pieces. Each of the ear pieces includes an ear tip, an audio receiver and an acoustic-to-electric transducer. The ear tip is capable of being inserted into an ear canal. The audio receiver is configured for recovering sound signals from audio electrical signals and transmitting the sounds signals to the ear canal via the ear tip. The acoustic-to-electric transducer is disposed on the ear tip, and configured for sensing vibration of an inner wall of the ear canal and generating an electrical signal in accordance with the vibration.

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to headphones, and more particularly, to an in-ear headphone with sound pick-up capability. 
     BACKGROUND 
     Headphones are widely used in modern electronic devices for providing audible sounds for users. An in-ear headphone (namely, earphone or ear-fitting headphone) is one type of headphones, which includes a pair of earpieces that can be inserted into user&#39;s ear canals. A headphone may be combined with a microphone to form an audio headset. The microphone serves as an acoustic sensing device, and normally includes an acoustic-to-electric transducer for converting sound waves like voices of the user into electrical signals that can then be amplified, transmitted, and output. 
     However, in a related audio headset, the microphone is normally somewhat distant from the user&#39;s mouth, thus the user may have to move the microphone close to his or her mouth in order to improve a signal-to-noise ratio of the microphone, which brings inconvenience to the user. Moreover, the microphone is exposed in the air, and thus ambient noise may be unavoidably picked up by the microphone. Therefore, a sound recognition of the microphone cannot satisfy the user&#39;s expectation or requirements. 
     Accordingly, the present disclosure provides an improved in-ear headphone to overcome the aforesaid problems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the embodiments can be better understood with reference to the following drawings. The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is an isometric view of an in-ear headphone according to an exemplary embodiment of the present disclosure, the in-ear headphone including earpieces having an acoustic-to-electric transducer. 
         FIG. 2  is a planar view of the earpiece of the in-ear headphone of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the earpiece of the in-ear headphone of  FIG. 1 . 
         FIG. 4  is a cross-sectional view of acoustic-to-electric transducer of the earpiece of the in-ear headphone of  FIG. 1 . 
         FIG. 5  is a cross-sectional view of an earpiece of an in-ear headphone according to another exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure will be described in detail below with reference to the attached drawings and embodiments thereof. 
       FIG. 1  is an isometric view of an in-ear headphone according to an exemplary embodiment of the present disclosure. The in-ear headphone  1  is also known as an earphone, and includes a headphone connector  11 , a headphone wire  13  and a pair of earpieces  15 . The headphone connector  11  is plugged into an audio source (not shown) such as a mobile phone, a portable media player, or other electronic devices, and is configured to receive audio electrical signals from the audio source. In fact, the headphone connector  11  may also be a wireless transmission element like a Bluetooth unit. The pair of earpieces  15  is electrically connected to the headphone connector  11  via the headphone wire  13 . In this embodiment, the headphone wire  13  is exposed outside of the earpiece  15 , and optionally, the wire  13  may be received inside of the earpiece  15 . When the in-ear headphone  1  is used by a user, one of the earpieces  15  can be inserted into a left ear canal of the user, and the other one of the earpieces  16  can be inserted into a right ear canal of the user. It is understood that this embodiment provides a stereo headphone, and the disclosure is also applicable to a mono one, i.e. the headphone includes only one earpiece. 
     Referring also to  FIGS. 2-3 , the earpiece  15  of the in-ear headphone  1  includes a housing  150 , an audio receiver  151 , an ear tip  153 , an acoustic-to-electric transducer  155 , and a preamplifier module  156 . 
     The audio receiver  151  is an electro-acoustic device serving as a listening part of the in-ear headphone  1  for performing sound reproduction under a standard non-leakage condition. The audio receiver  151  is a main component for recovering the sound signals from the audio electrical signals, and the audio receiver  151  may further transmit the sound signals to the user&#39;s ear canal via the ear tip  153 . 
     The ear tip  153  may be a plastic component, for example, the ear tip  153  may be made of silicone material. The ear tip  153  is designed to have an outer profile substantially matching an internal profile of an ear canal, so as to enable the ear tip  153  to be inserted into the ear canal of the user. In addition, the ear tip  153  has a configuration to enable an external surface thereof to abut on an inner wall of the ear canal when the ear tip  153  is inserted into the ear canal of the user. 
     The ear tip  153  defines an accommodating space which opens at both ends thereof, the audio receiver  151  may be received in the accommodating space. One end of the ear tip  153  is configured as a connecting end, which is fixed to an opening (not shown) of the housing  150  and surrounds an end of the audio receiver  151 ; the other end of the ear tip  153  is communicated with the ear canal of the user to enable the sound signals provided by the audio receiver  151  to be transmitted to the user&#39;s ear canal. 
     The acoustic-to-electric transducer  155  is disposed on the ear tip  153 , and is configured for sensing vibration of the inner wall of the ear canal when the user speaks, so as to pick up sounds made by the user, which is also called bone conduction. Moreover, the acoustic-to-electric transducer  155  can also generate an electrical signal corresponding to the vibration. 
     In one embodiment, the acoustic-to-electric transducer  155  has a ring-shaped structure and is disposed at an external surface of the ear tip  153 . To receive the acoustic-to-electric transducer  155 , an annular groove  1531  is correspondingly formed at the external surface of the ear tip  153 , as illustrated in  FIG. 2 . In particular, the annular groove  1531  may have a depth substantially equal to a thickness of the acoustic-to-electric transducer  155 . As such, an external surface of acoustic-to-electric transducer  155  is coplanar with the external surface of the ear tip  153 , such that the external surface of the acoustic-to-electric transducer  155  can also abut against the inner wall of the ear canal to sense the vibration thereof upon the condition that the ear tip  153  is inserted into the ear canal. Moreover, with this configuration, the acoustic-to-electric transducer  155  can also prevent air flow from leaking from the ear canal. 
       FIG. 4  is a cross-sectional view of acoustic-to-electric transducer  155  of the earpiece  15 . The acoustic-to-electric transducer  155  may be a piezoelectric film (for example, a piezoelectric ceramic film) with a multi-layer structure. The acoustic-to-electric transducer  155  includes a piezoelectric film layer  1551 , a first electrode layer  1553 , a second electrode layer  1555 , a first shielding layer  1557  and a second shielding layer  1559 . The first shielding layer  1557 , the first electrode layer  1553 , the piezoelectric film layer  1551 , the second electrode layer  1557  and the second shielding layer  1559  are arranged in a sequence as shown in  FIG. 4 . 
     The piezoelectric film layer  1551  is a piezoelectric component made by piezoelectric ceramic. The piezoelectric film layer  1551  may provide piezoelectric effect when a pressure is perpendicularly applied thereto, and accordingly piezoelectric charges are induced and accumulated at two opposite surfaces (namely, a top surface and a bottom surface thereof as illustrated in  FIG. 4 ) of the piezoelectric film layer  1551 . Since the acoustic-to-electric transducer  155  abuts against the inner wall of the ear canal, the pressure is typically generated in responsive to vibration of the inner wall of the ear canal. Furthermore, due to the piezoelectric charges, an electrical signal corresponding to the vibration is generated at the piezoelectric film layer  1551 , and an amplitude of the electrical signal is in proportion to a magnitude of the vibration. 
     The first electrode layer  1553  and the second electrode layer  1555  are respectively formed at opposite sides of the piezoelectric film layer  1551  to sandwich and electrically contact the piezoelectric film layer  1551  therebetween. The first electrode layer  1553  is further electrically connected to the preamplifier module  156  via a first connecting wire  1561 , and the second electrode layer  1555  is further electrically connected to the preamplifier module  156  via a second connecting wire  1563 . The first electrode layer  1553  and the second electrode layer  1555  may output the electrical signal generated by the piezoelectric film layer  1551  to the preamplifier module  156  for pre-amplification. 
     The first shielding layer  1557  and the second shielding layer  1559  are respectively formed adjacent to the first electrode layer  1553  and the second electrode layer  1555 . The first shielding layer  1557  and the second shielding layer  1559  can cooperatively protect and insulate the piezoelectric film layer  1551 . In particular, the first shielding layer  1557  and the second shielding layer  1559  may be configured to cooperatively form a one-piece U-shape structure, that is, a connection portion  1558  may be formed to connect corresponding ends of the first shielding layer  1557  and the second shielding layer  1559 , as shown in  FIG. 4 . 
     In particular, a total thickness of the acoustic-to-electric transducer  155  may be in a range from 95 μm (micrometers) to 105 μm, and preferably, 100 μm. Furthermore, because the electrical signal is generated according to the pressure applied to the acoustic-to-electric transducer  155 , to ensure a signal-to-noise ratio (SNR) of the electrical signal, the acoustic-to-electric transducer  155  may be designed to have a large area as possible. 
     In operation, the ear tip  153  is inserted into the ear canal of the user, with the external surface of the acoustic-to-electric transducer  155  abutting on an inner wall of the ear canal. The audio receiver  151  converts the audio electrical signals received from the headphone connector  11  into sound signals, and transmits the sound signals to the ear canal of the user via the ear tip  153 . 
     When the user speaks, the inner wall of the ear canal vibrates corresponding to sound made by the user, the vibration of the inner wall of the ear canal is sensed by the acoustic-to-electric transducer  155 . Due to piezoelectric characteristics of the piezoelectric film layer  1551 , piezoelectric effect occurs on the piezoelectric film layer  1551  of the acoustic-to-electric transducer  155 , and an electrical signal corresponding to vibration of the inner wall of the ear canal is generated. In other words, the sound of the user can be picked up by the acoustic-to-electric transducer  155  in a form of the electrical signal. The electrical signal is then transmitted to the preamplifier module  156 , and the preamplifier module  156  performs a pre-amplification on the piezoelectric signal. Thereafter, the electrical signal can be output for signal processing. 
     In the in-ear headphone  1  as provided in the present disclosure, an acoustic-to-electric transducer  155  is disposed on the ear tip  153  of the ear piece  15 . With this configuration, the acoustic-to-electric transducer  155  can be inserted into the ear canal of the user accompanying with the ear tip  153 , and thus can sense the vibration of the inner wall of the ear canal when the user speaks, so as to pick up the sound made by the user. With this sound pick-up capability, it is unnecessary for the user to hold a microphone close to his or her mouth, and thus operation convenience of in-ear headphone  1  is improved. Furthermore, the acoustic-to-electric transducer  155  is not exposed in the air since it is inserted into the ear canal, which can prevent the acoustic-to-electric transducer  155  from picking up ambient noise, thereby improving the sound recognition. 
       FIG. 5  is a cross-sectional view of an earpiece of an in-ear headphone according to an alternative embodiment of the present disclosure. The in-ear headphone in the alternative embodiment is similar to the above-described in-ear headphone  1 , but differs in that an acoustic-to-electric transducer of an earpiece  25  of the in-ear headphone  200  includes at least two transducer units  2531  and  2532 . 
     Specifically, the acoustic-to-electric transducer of an earpiece  25  includes a first transducer unit  2551  and a second transducer unit  2552 . Both of the first transducer unit  2551  and the second transducer unit  2552  are in an arc shape. Correspondingly, a first sub-groove  2531  and a second sub-groove  2532  are formed at an ear tip  253  of earpiece  25  to receive the first transducer unit  2551  and the second transducer unit  2552 . The transducer unit  2551  and the second transducer unit  2552  are both piezoelectric film with a configuration substantially the same as illustrated in  FIG. 4 . It is noted that in other embodiment, the transducer units  2551  may alternatively have other shapes. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.