Abstract:
A contact type electret condenser pickup to deliver high anti noise, top talking quality, and comprehensive range of applications includes a casing provided with an accommodation chamber to contain an O-ring, a vibration part, an insulation packing, a back plate retaining ring containing a back plate, a conductive connection ring, and a circuit board horizontally placed in sequence; vibration of a sound of a user is transmitted to the vibration part; then an inertia vibration of the metal sheet changes capacitance between the vibration part and the back plate; the changed vibration is converted through the circuit board set into voltage of alternating signals for output variable according to changes of vibration.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (a) Field of the Invention 
         [0002]    The present invention is related to a contact type electret condenser pickup, and more particularly, to one that contacts human skin to pick up micro vibration generated during talking to realize electro-acoustic transduction. 
         [0003]    (b) Description of the Prior Art 
         [0004]    How to maintain clear and effective communications in a highly noisy environment, e.g., fire fighting site or a battlefield has been a problem desperately to be solved. Currently, a contact type vibration pickup is usually used for electro-acoustic transducer essentially based on electromagnetic and piezoelectric working principle. Both types of the transducers however have been found with certain problems in their talking clarity, output sensitivity, and anti noise performance. 
         [0005]    A condenser pickup of the prior art has a thinner metal diaphragm serving as a plate (a vibration part) of a condenser and a fixed thicker metal plate facing the diaphragm as a fixed plate of capacitance (back plate); an air medium existing between the vibration part and the back plate functions as a condenser; and an elastic structure of the thinner metal diaphragm is capable of picking up vibration of external acoustic wave to create minor axial displacement thus to change an air gap between the vibration part and the back plate resulting in changed capacity of electric charge of the condenser comprised of both plates. Changed electric charge resulted from changed acoustic pressure further change in output voltage, thus to avail a current in specific size and direction. A condenser pickup provides advantage of good frequency response, low noise level, and low distortion; and disadvantages of comparatively complicated output interface circuit, lower level of output signals, being vulnerable to interference by external stray signals, and preventing from forming a complete set with associate apparatus. 
       SUMMARY OF THE INVENTION 
       [0006]    The primary purpose of the present invention is to provide a contact type electret condenser pickup that delivers high anti noise, top talking quality, and comprehensive range of applications. 
         [0007]    To achieve the purpose, a contact type electret condenser pickup of the present invention includes an casing provided with an accommodation chamber to receive an O-ring, a vibration part, an insulation packing, a back plate retaining ring disposed with a back plate, a conductive connection ring, and a circuit board set in sequence; wherein, the O-ring, the vibration part, and the insulation packing jointly allow a space for the vibration part to realize vibration; the back plate is electrically connected to the circuit board set through the conductive connection ring; an open end of the casing is inwardly curved in radius towards the circuit board set and maintains constant contacts among the O-ring, the vibration part, the insulation packing, the back plate, the back plate retaining ring, and the conductive connection ring received in the casing. 
         [0008]    The vibration part includes a metal sheet and a weight with the weight fixed to a side of the metal sheet in facing the O-ring; or alternatively the vibration part includes a support and a metal sheet with the metal sheet fixed to the support of the vibration part by means of a cantilever structure. 
         [0009]    The casing may be made in a long and thin tube that allows it to be inserted into a human&#39;s acoustic meatus with the vibration part, the O-ring, the back plate, and the circuit board set overlapped and received in the accommodation chamber of the casing in a direction vertically to the open end of the casing. 
         [0010]    Accordingly, the contact electret condenser pickup of the present invention has its vibration part to be made of a metal sheet fixed on the back of the metal sheet a weight or a metal sheet secured in position by means of a cantilever structure so to allow vibration of one&#39;s throat while talking to be transmitted to the vibration part; then an inertia vibration of the metal sheet changes capacitance between the vibration part and the back plate; the changed vibration is converted through the circuit board set into voltage of alternating signals for output variable according to changes of vibration. Whereas a thickness of the metal sheet is one thousand times of that of the vibration diaphragm, the metal sheet will not vibrate when subject to acoustic wave, meaning, the metal sheet is not affected by noise thus to provide sound insulation. When compared to the prior art, the present invention is not affected by noise, providing high noise resistance, top talking quality, and delivers a comprehensive range of applications. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a first preferred embodiment of the present invention. 
           [0012]      FIG. 2  is a schematic view showing a vibrating part of the first preferred embodiment of the present invention. 
           [0013]      FIG. 3  is a sectional view showing the first preferred embodiment of the present invention. 
           [0014]      FIG. 4  is a perspective view of a second preferred embodiment of the present invention. 
           [0015]      FIG. 5  is a schematic view showing a vibration part of the second preferred embodiment of the present invention. 
           [0016]      FIG. 6  is a sectional view showing the second preferred embodiment of the present invention. 
           [0017]      FIG. 7  is a schematic view showing a construction of a circuit board in the present invention. 
           [0018]      FIG. 8  is a perspective view of a third preferred embodiment of the present invention. 
           [0019]      FIG. 9  is a schematic view showing a sectional view of the third preferred embodiment as assembled. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Referring to  FIGS. 1 ,  2 ,  3 , and  7  for a first preferred embodiment of the present invention, a skin contact type electret condenser pickup is essentially comprised of a metal casing, an O-ring  2 , a vibration part  3 , an insulation packing  4 , a back plate  5 , a back plate retaining ring  6 , a metal connection ring  7 , and a circuit board set  8 . The metal casing  1  is related to a cylindrical box with an open end. The O-ring  2  has an outer diameter to merely match with an inner diameter of the metal casing  1  and is placed in the metal casing  1  to contact an inner bottom of the metal casing  1 . 
         [0021]    The vibration part  3  includes a circular metal sheet  31  and a circular weight  32  with the weight  32  fixed to one side of the metal sheet  31 ; a diameter of the metal sheet  31  is merely matching with the inner diameter of the metal casing  1 ; the side of the metal sheet  31  fixed with the weight  32  is laterally placed on the O-ring; both circular cavities respectively of the weight  32  and the O-ring are placed corresponding to each other; and both of the metal sheet  31  and the weight  32  are pushed by the O-ring to stay clear out of the inner bottom of the metal casing  1 . The insulating packing  4  placed on the metal sheet  31  is in an outer diameter to merely match with an inner diameter of the metal casing  1 . 
         [0022]    The back plate retaining ring  6  placed on the insulation packing  4  relates to a hollow cylindrical structure having an outer diameter to merely match with the inner diameter of the metal casing  1 . The back plate  5  relates to a circular metal plate having one side attached with an electret thin diaphragm and a diameter matching with an inner diameter of the back plate retaining ring  6 ; the back plate is inserted in the back plate retaining ring  6  with the side attached with the diaphragm contacting the insulation packing  4 ; and both of the electret diaphragm and the metal sheet  31  keep a certain distance from each other by means of the insulation packing  4 . 
         [0023]    The metal connection ring  7  related to a hollow cylindrical structure has its outer diameter to merely match with the inner diameter of the back plate retaining ring  6  and is inserted into the back plate retaining ring  6  with one side contacting and electrically connecting to the back plate  5 . The circuit board set  8  includes a circular circuit board  81  and a designated chip  82  attached to one side of the circuit board  81 ; the side of the circuit board  81  attached with the chip  82  contacts another side of the metal connection ring  7  and keeps electrically connected to the metal connection ring  7 ; the circuit board  81  has an outer diameter that is merely matching with the inner diameter of the metal casing  1 ; the metal casing  1  constitutes a cylindrical space in conjunction with the circuit board  81 ; and the opening end of the metal casing inwardly curved in radius towards the circuit board  81  and maintains constant contacts among the O-ring  2 , the metal sheet  31 , the insulation packing  4 , the back plate  5 , the back plate retaining ring  6 , and the metal connection ring  7 . 
         [0024]    A second preferred embodiment of the present invention as illustrated in  FIGS. 4 ,  5 ,  6 , and  7  differs from the first preferred embodiment only in the vibration part  3 . A vibration part  3  of the second preferred embodiment of the present invention is comprised of a circular support  33  and a circular metal sheet  34  secured to the circular support  33  by means of a cantilever structure; the metal sheet  34  is in a diameter smaller than an inner diameter of the circular support; the metal sheet  34  is located within a circular chamber of the circular support  33 ; and the metal sheet  34 , the cantilever structure, and the circular support  33  are made an integral part using a circular metal plate in a punching process. 
         [0025]    The present invention is also applicable to an ordinary condenser pickup Additional to both electret condenser pickups as disclosed in the first and the second preferred embodiments. When applied in the ordinary condenser pickup, it takes only to introduce a bias voltage through the circuit board into where between the vibration part and the back plate. 
         [0026]    Now referring to  FIGS. 8 and 9 , a third preferred embodiment of the present invention made in a compact size that can be placed within a user;¦s acoustic meatus is comprised of a metal casing  10 , a vibration part  20 , a spacer  30 , a back plate  40 , a circuit board set  50 , a lead wire  60 , and a fastening elastic plate  70 . Wherein, the metal casing  10  is related to a long and thin tube that allows it to be appropriately inserted into the user;¦s acoustic meatus; the vibration part  20 , the spacer  30 , the back plate  40 , and the circuit board set  50  are laminated in sequence before being placed in an accommodation chamber  14  vertically along an open end  13  of a body  11  of the metal casing  10 ; the lead wire  60  is electrically connected to the circuit board set  50  and extends out of the metal casing  10  along a cap  12  on one end of the metal casing  10 ; the vibration part  2  is related to a rectangular or an oval beam structure of elastic cantilever; the back plate  40  is attached with an electret HD organic material; the spacer  30  is made of organic material with insulation property to become a condenser containing an air medium layer between the vibration part  20  and the back plate  40 ; the circuit board set  50  includes a circuit board  51  and a designated IC placed on the circuit board  51 ; and the fastening elastic plate  70  is disposed at where between the circuit board set  50  and an inner wall of the metal casing  10 . 
         [0027]    Accordingly, the vibration part  20 , the spacer  30 , the back plate  40 , and the circuit board unit  50  are tightly laminated in sequence to ensure good contact among all members. The fastening elastic plate  70  is comprised of a press plate  71  compressing against the circuit board set  50  and two support arms  72  respectively extend from both ends of the press plate  71 ; and a top of each support arm  72  holds contacts the inner wall of the metal casing  10 . 
         [0028]    In the third preferred embodiment, the long and thin casing  10  receives in sequence the vibration part  20 , the spacer  30 , the back plate  40  and the circuit board set  50  laminated into an integral part to allow the casing to be placed into the user&#39;s acoustic meatus. Meanwhile, the vibration part  20 , the spacer  30 , the back plate  40  and the circuit board set  50  are inserted into a hollow chamber of the casing  10  in a direction vertical to an open end of the casing  10  to allow them to be placed in the user&#39;s acoustic meatus. 
         [0029]    As the user talks, his/her cranium vibrates and a frequency of the vibration is transmitted to the vibration part for a dead load of the cantilever elastic structure of the vibration part  20  to pick up minute axial displacement thus to change an air gap between the vibration part and the back plate and further changes electric charge of the capacitance comprised of the vibration part and the back plate. Whereas capacitance is changed by the present invention without collecting sound waves, the present invention is not affective by any air-induced noise to provide high noise resistance and top talking quality. 
         [0030]    The present invention is characterized in a condenser comprised of a vibration part and a back plate with variable gap to transmit a talking frequency of the user to the vibration part where picks up minute axial displacement crated by external vibration by means of an elastic cantilever structure or a metal sheet attached with a weight thus to change the air gap between the vibration part and the back plate, and further to change electric charge of a condenser comprised of the vibration part and the back plate to output alternating voltage. Consequently, the present invention is adaptable to various environment filled with higher level of noise including a fire fighting site and battlefield. 
         [0031]    It is to be noted that the preferred embodiments disclosed in the specification and the accompanying drawings are not limiting the present invention; and that any construction, installation, or characteristics that is same or similar to that of the present invention should fall within the scope of the purposes and claims of the present invention.