Abstract:
An earphone jack ( 100 ) for a portable electronic device includes a detecting module ( 20 ) and a jack module ( 30 ). The detecting module is configured for detecting if a plug of an earphone has been connected to the earphone jack. The jack module is connected to the detecting module, and includes a connecting hole ( 32 ) configured for receiving the plug defined therein, two earphone connectors ( 333, 334 ) configured for connecting the plug, a contacting member ( 35 ) connected to the detecting module, and a movable member ( 331 ) separately connected to the contacting member. Therefore, the detecting module can detect the plug connected to the earphone jack without causing any instantaneous current in the jack module and the plug.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention generally relates to earphone jacks, particularly to an earphone jack preventing damage from instantaneous currents. 
     2. Description of related art 
     Nowadays, many portable electronic devices such as mobile phones or CD players, have earphone jacks configured for connecting with an earphone to play audio signals. Generally, an earphone is connected to a jack of a portable electronic device through a plug. The portable electronic device detects the plug, and electronic signals, such as speech or music, provided by the portable electronic device can be converted into audio signals by the earphone. 
     However, when using most conventional earphone jacks, portable electronic devices detect earphones connected thereto by sending electrical detection signals to the jack and, subsequently, receiving electrical response signals from the jack. When an earphone is connected to a jack, the electrical signals for detecting the earphone may cause an instantaneous current passing through the jack and the earphone. The instantaneous current may cause cacophony, which impairs the quality of the audio signals converted by the earphone. Furthermore, the instantaneous current may damage circuits of the earphone and the jack. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the new earphone jack can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the new earphone jack. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a block, schematic, circuit diagram of an earphone jack, according to an exemplary embodiment. 
         FIG. 2  is a schematic view of connecting an earphone to the earphone jack shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  shows an earphone jack  100  according to an exemplary embodiment. The earphone jack  100  can be installed in a portable electronic device, such as a mobile phone or a CD player, to convert electrical signals provided thereby into audio signals. The earphone jack  100  includes a power supply connector  10 , a detecting module  20  and a jack module  30 . The power supply connector  10  is used to connect to a power supply (not shown), which provides electrical power to the earphone jack  100 . The detecting module  20  is connected to the power supply connector  10 . The jack module  30  is connected to the detecting module  20  when an earphone is not connected to the jack module  30 . 
     The detecting module  20  includes a transistor  210 , a first resistor  220 , a second resistor  230 , a detecting connector  240  and a first ground  260 . The first resistor  220  has one end connected to the power supply connector  10  and another end connected to a collector of the transistor  210 . The second resistor  230  has one end connected to the power supply connector  10  and another end connected to a base of the transistor  210 . The detecting connector  240  has one end connected between the first resistor  220  and the collector of the transistor  210 , and another end connected to a circuit (not shown) of the portable electronic device for detecting earphones connected to the jack module  30 . An emitter of the transistor  210  is connected to the first ground  260 . 
     The jack module  30  includes a case  32  configured for being installed in portable electronic devices, a connecting hole  33  defined in the case  32  and configured for receiving an earphone plug, a contacting member  35  mounted on the case  32 , and five receiving apertures  321 ,  322 ,  323 ,  324  and  325  defined in the case  32 . The receiving apertures  321 - 325  all communicate with the receiving hole  33 . The contacting member  35  is connected to the power supply  10  through the second resistor  230 , and the base of the transistor  210  is connected between the second resistor  230  and the contacting member  35 . 
     The jack module  30  further includes a second ground  311 , a third resistor  312 , a first circuit connector  313 , a second circuit connector  314 , a third ground  315 , a movable member  331 , a retaining member  332 , a left earphone connector  333 , a right earphone connector  334  and a grounding connector  335 . The movable member  331 , the retaining member  332 , the left circuit connector  333 , the right earphone connector  334  and the grounding connector  335  are all made of elastic conductive materials, such as metal, and are all received in the case  32 . 
     The movable member  331  is received in a first receiving aperture  321  and connected in series to the third resistor  312 . The third resistor  312  is connected in series to the second ground  311 . The retaining member  332  is received in a second receiving aperture  322 . The left earphone connector  333  is received in a third receiving aperture  323  and connected to the first circuit connector  313 . The right earphone connector  334  is received in a fourth assembling aperture  324  and connected to the second circuit connector  314 . The first circuit connector  313  and the second circuit connector  314  are connected to inner circuits of the portable electronic device. Thus, the portable electronic device can provide electrical signals to the jack module  30  through the first circuit connector  313  and/or the second circuit connector  314 . The grounding connector  335  is received in a fifth receiving aperture  325  and is connected to the third ground  315 . The movable member  331 , the retaining member  332 , the left earphone connector  333 , the right earphone connector  334  and the grounding connector  335  are all exposed from their corresponding receiving apertures, and all extend into the connecting hole  33 . 
     In assembly, the earphone jack  100  is installed in a portable electronic device, such as a mobile phone or a CD player. The power supply connector  10  is connected to a power source to obtain electrical power. The contacting member  35  is positioned to be in contact with the movable member  31 , thereby electrically connecting the detecting module  20  to the jack module  30 . The connecting hole  33  is exposed from the portable electronic device. The detecting connector  240  is connected to a circuit of the portable electronic device for detecting earphones connected to the jack module  30 . 
     As seen in  FIG. 1 , when earphones have not been inserted into the connecting hole  33 , the contacting member  35  remains in contact with the movable member  31 . Thus, the power supply connector  10 , the second resistor  230 , the third resistor  312  and the second ground  311  are connected in series. Therefore, an electrical potential U 1  located on the base of the transistor  210  is reduced by the third resistor  312 . By regulating the resistance of the second resistor  230  and the third resistor  312 , the electrical potential U 1  is regulated to be less than a turn-on voltage of the transistor  210 . Thus, the transistor  210  is turned off, and the detecting connector  240  connected to the collector of the transistor  210  outputs a high electrical potential. The high electrical potential can be received by the portable electronic device. If the portable electronic device detects that no plugs have been connected to the jack module  30 , it does not send signals to the jack module  30 . 
     Referring to  FIG. 2 , a plug  50  of an earphone (not shown) is connected to the jack module  30 . The plug  50  has a substantially cylindrical shape corresponding to the shape of the connecting hole  33 . The plug  50  includes four connecting portions  510 ,  520 ,  530 ,  540 , and a plurality of annular insulated portions  560  configured for separating the connecting portions  510 ,  520 ,  530 ,  540 . A first connecting portion  510  is formed on a base of the plug  50  and is configured for grounding. A second connecting portion  520  is formed adjacent to the first connecting portion  510  and a third connecting portion  530  is formed adjacent to the second connecting portion  520 . The second and third connecting portions  520 ,  530  are configured for connecting to the left and right speakers of the earphone, respectively. A fourth connecting portion  540  is formed on an end of the plug  50  adjacent to the third connecting portion  530 . A diameter of the fourth connecting portion  540  is less than the diameter of the third connecting portion  530 , and an inclined surface  550  is formed between the third connecting portion  530  and the fourth connecting portion  540 . 
     In use, the plug  50  is inserted into the connecting hole  33 . The first connecting portion  510  contacts with the grounding connector  335  to connect to the ground. The second connecting portion  520  and the third connecting portion  530  are respectively connected to the left earphone connector  333  and the right earphone connector  334  to obtain electrical signals. The first connecting portion  510  resists the movable member  331  to separate from the contacting member  35 . The retaining member  332  contacts the fourth connecting portion, and resists the inclined surface  550  to retain the plug  50  in the connecting hole  33 . 
     When the movable member  331  is separated from the contacting member  35  by the plug  50 , the power supply connector  10 , the transistor  210 , the first resistor  220 , the second resistor  230  and the first ground  260  are connected in series. An electrical potential of the power source, which is higher than the turn-on voltage of the transistor  210 , is input into the base of the transistor  210 . Thus, the transistor  210  is turned on, and the detecting connector  240  outputs a low electrical potential. The low electrical potential is received by the portable electronic device. If the portable electronic device detects that the plug  50  is connected to the jack module  30 , it sends signals to the earphone through the jack module  30 . 
     Understandably, when the plug  50  is connected to the jack module  30 , the movable member  331  is separated from the contacting member  35 . The detecting module  20  is insulated with the jack module  30  and the plug  50 , and electrical signals for detecting the plug  50  pass through the detecting module  20 , but not the jack module  30  and the plug  50 . As such, no instantaneous current will be formed in the jack module  30  and the plug  50 . Therefore, the jack module  30  and the plug  50  are protected from instantaneous current, and an audio quality of the earphone is improved. 
     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.