Abstract:
An earphone plug with a mode switching function is presented. The earphone plug includes a terminal and a switching device. The terminal has a plurality of electrodes to transmit signals. The switching device is combined with the terminal, and is capable of switching between a first mode and a second mode, and part of the electrodes of the terminal are electrically connected together, so as to achieve mode switching to perform processing on different transmission signals.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to an earphone plug, and more particularly to an earphone plug with a mode switching function, which is selectively applicable to mobile phones or music players by switching a control mode between a three-electrode mode and a four-electrode mode. 
     2. Related Art 
     Earphone is an indispensable accessory in portable electronic products for providing audio information. Earphone plugs are divided into conventional three-pole earphone plugs and conventional four-pole earphone plugs which are respectively applicable to portable electronic products with different functions.  FIGS. 1 and 2  are respectively external views of a conventional three-pole earphone plug  1  and a conventional four-pole earphone plug  2 . 
     The three-pole earphone plug  1  includes three electrodes  1   a ,  1   b , and  1   c , for respectively transmitting a left channel signal, a right channel signal, and a ground signal, so that the earphone plug  1  is applicable to a personal portable music device such as MP3 to provide stereo music information. However, the earphone plug  1  can only output sound due to the structural limit, and cannot provide sound receiving function, so that it cannot be used as a hand-free receiver for mobile phones. 
     The four-pole earphone plug  2  includes four electrodes  2   a ,  2   b ,  2   c , and  2   d , for respectively transmitting a left channel signal, a right channel signal, a microphone signal, and a ground signal, so that the earphone plug  2  can be used as a hand-free receiver for mobile phones. Accordingly, due to the structure, the earphone plug  2  with four electrodes cannot be used in conjunction with three-pole earphone jacks, so that consumers must take number of poles into consideration when choosing earphones. As conventional earphone plugs can only be fitted to corresponding earphone jacks, the use of earphones is limited, and the consumer must additionally buy different types of earphone plugs to meet requirements for different electronic products, especially when the earphone is used between products such as mobile phones and music devices, which will result in economic burden. 
     In order to solve the problem, an adapter has been available on the market, which is used for connection to a four-pole earphone plug, such that the earphone plug is applicable to a three-pole earphone jack, thereby eliminating the use limit of the four-pole earphone plug. However, there still exist problems that the consumers still have to spend money to purchase the adapter and the adapter may easily be lost which causes inconvenience in use. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to an earphone plug with a mode switching function, which includes a terminal and a switching device. The terminal has a plurality of electrodes for transmitting signals. The switching device is combined with the terminal, and is capable of switching between a first mode and a second mode, and part of the electrodes of the terminal are electrically connected together, so as to achieve mode switching to perform processing on different transmission signals. 
     In order to achieve the above objectives, according to the present invention, the terminal has a first electrode, a second electrode, a third electrode, and a fourth electrode, and further includes a first conductive member and a second conductive member, the switching device has a movable sleeve disposed at a rear end of the terminal, and the movable sleeve has a metal sheet for being pressed against the first conductive member and second conductive member when the earphone plug is switched from the first mode to the second mode, such that the first conductive member and the second conductive member are electrically connected, the corresponding third electrode and fourth electrode are conducted, and the earphone plug is switched from a four-electrode state to a three-electrode state. Therefore, the earphone plug of the present invention is applicable to mobile phones and music players at the same time. 
     In order to achieve the above objectives, according the present invention, a fixed sleeve is connected to the rear end of the terminal, a plastic member is embedded between the fixed sleeve and the terminal, the plastic member has a pair of stopping blocks, and the movable sleeve correspondingly has a pair of guide grooves disposed thereon, so as to limit the rotation position of the movable sleeve relative to the plastic member. 
     In order to achieve the above objectives, according the present invention, the fixed sleeve has a marking point, the movable sleeve has a bushing sleeved outside, and the bushing has an indication area corresponding to the marking point to indicate a position when switching. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below for illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is an external view of a conventional three-pole earphone plug; 
         FIG. 2  is an external view of a conventional four-pole earphone plug; 
         FIG. 3  is an external view of an earphone plug with a mode switching function according to the invention; 
         FIG. 4  is an exploded view of the earphone plug with a mode switching function according to the invention; 
         FIG. 5  is a transverse sectional view (I) of the earphone plug with a mode switching function according to the invention; 
         FIG. 6  is a partial axial sectional view (I) of the earphone plug with a mode switching function according to the invention; 
         FIG. 7  is a transverse sectional view (II) of the earphone plug with a mode switching function according to the invention; and 
         FIG. 8  is a partial axial sectional view (II) of the earphone plug with a mode switching function according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, embodiments of an earphone plug with a mode switching function in the present invention are described with reference to the accompanying drawings. 
       FIG. 3  is an external view of an earphone plug with a mode switching function according to the invention. Referring to  FIG. 3 , the earphone plug  100  includes a terminal  10 , a switching device  20 , a fixed sleeve  30 , and a wire  40 . 
       FIG. 4  is an exploded view of the earphone plug with a mode switching function according to the invention. Referring to  FIG. 4 , the terminal  10  has a first electrode  11 , a second electrode  12 , a third electrode  13 , and a fourth electrode  14  disposed thereon in sequence from left to right, and an insulating portion  15  connected to the rear of the fourth electrode  14 . The insulating portion  15  has a first terminal groove  16 , a second terminal groove  17 , a hollow terminal portion  18 , and a tail end  19 . The first terminal groove  16  and the second terminal groove  17  are clamped by a first conductive member  50  and a second conductive member  51  respectively. 
     The first conductive member  50 , the second conductive member  51 , the terminal portion  18 , and the tail end  19  serve as contact portions for electrical connection, to be welded and connected to a left channel signal line, a right channel signal line, a microphone signal line, and a ground signal line (not shown) in the wire  40  respectively. The first electrode  11 , the second electrode  12 , the third electrode  13 , and the fourth electrode  14  are electrically connected to the first conductive member  50 , the second conductive member  51 , the terminal portion  18 , and the tail end  19  respectively. The main structural feature of the terminal  10  in the present invention is a four-pole terminal in the prior art, and thus will not be described herein again. 
     The switching device  20  includes a movable sleeve  21 , which has a pair of hollow guide grooves  22  opened at transverse positions, and a pair of fastening grooves  23  disposed on an outer periphery at axial positions and in communication with the guide grooves  22 . The movable sleeve  21  has a combination groove  21   a  disposed on an inner periphery, and the combination groove  21   a  has a positioning portion  21   b  recessed on two sides thereof respectively. The switching device  20  further includes a bushing  24 , which has a pair of fastening blocks  25  disposed on an inner surface thereof to fit the fastening grooves  23  of the movable sleeve  21 , and an indication area  26  disposed on an outer periphery thereof. In addition, the switching device  20  further includes a revised U-shaped elastic metal sheet  27  fixed into the combination groove  21   a  of the movable sleeve  21  in a mechanical manner or other equivalent manners, and the metal sheet  27  has a first contact  271  and a second contact  272  disposed thereon, and two foot portions  273  disposed on two sides thereof. The foot portions  273  can be combined with the positioning portion  21   b.    
     The wire  40  extends though one end of the fixed sleeve  30 , and a plastic member  31  is combined with the other end of the fixed sleeve  30 . The plastic member  31  is embedded between the insulating portion  15  of the terminal  10  and the fixed sleeve  30 , and has a first perforation  32 , a second perforation  33 , and a pair of stopping blocks  34  disposed at an end on an outer periphery. When the plastic member  31  is sleeved on the insulating portion  15  of the terminal  10 , the first perforation  32  and the second perforation  33  fit the first conductive member  50  and the second conductive member  51 , so that the first conductive member  50  and the second conductive member  51  partially protrude from the outer periphery of the plastic member  31 . The fixed sleeve  30  is provided to assemble the movable sleeve  21 , and the stopping blocks  34  of the fixed sleeve  30  are placed in the guide grooves  22  of the movable sleeve  21 , so as to limit the displacement when the movable sleeve  21  rotates relative to the fixed sleeve  30  in a transverse direction. When the movable sleeve  21  rotates relative to the fixed sleeve  30 , the metal sheet  27  of the movable sleeve  21  selectively contacts the first conductive member  50  and the second conductive member  51 . Through the fitting of the fastening blocks  25  of the bushing  24  and the fastening grooves  23  of the movable sleeve  21 , the user can directly control the bushing  24  to drive the movable sleeve  21  to perform switching action. Furthermore, a marking point  35  is disposed on an outer surface of the fixed sleeve  30 , for alignment with the indication area  26  of the bushing  24  to indicate the state position. For example, in the invention, if the marking point  35  and the indication area  26  are separated, a first mode is indicated, and if they are aligned, a second mode is indicated. 
     It should be noted that, a magnetic ring  60  is disposed inside the plastic member  31 , for eliminating noise of the earphone plug  100 . 
       FIG. 5  is a transverse sectional view (I) of the earphone plug with a mode switching function according to the invention. Referring to  FIG. 5 , the earphone plug  100  is in the first mode, and the metal sheet  27  of the movable sleeve  21  is away from the first conductive member  50  of the terminal  10  without contact there-between. 
       FIG. 6  is an axial sectional view (I) of the earphone plug with a mode switching function according to the invention. Referring to  FIG. 6 , as the first conductive member  50  and the second conductive member  51  are respectively in an independent state when the earphone plug  100  of the invention is in the first mode, the terminal  10  is in communication with the left channel signal line, the right channel signal line, the microphone signal line, and the ground signal line of the wire  40 , and the earphone plug  100  is correspondingly applicable to four-electrode earphone jacks, especially mobile phones with a voice call function. It should be mentioned that, in the invention, an annular bump  251  is disposed transversally on an inner periphery of the bushing  24 , and is positioned in the guide grooves  22  of the movable sleeve  21  for secure positioning. 
       FIG. 7  is a transverse sectional view (II) of the earphone plug with a mode switching function according to the invention. Referring to  FIG. 7 , the bushing  24  is controlled to drive the movable sleeve  21  to rotate, such that the earphone plug  100  is switched from the first mode to the second mode, and the metal sheet  27  of the movable sleeve  21  contacts the first conductive member  50 . 
       FIG. 8  is an axial sectional view (II) of the earphone plug with a mode switching function according to the invention. Due to the displacement of the movable sleeve  21 , the first contact  271  and second contact  272  of the metal sheet  27  contact the first conductive member  50  and the second conductive member  51  respectively, such that the first conductive member  50  and the second conductive member  51  are electrically connected. In this way, the corresponding electrodes are in communication, the microphone signal and the ground signal of the earphone plug  100  are switched into an independent ground signal, and the earphone plug  100  is correspondingly applicable to three-electrode earphone jacks, especially music players such as MP3s. 
     Although the switching device  20  in the invention switches the mode by rotation, the switching device  20  can also change the mode by other equivalent or similar means, for example, sliding operation, which also falls within the technical scope of the invention. 
     In the earphone plug with a mode switching function of the invention, a switching device with a metal sheet is used, during the rotation relative to a terminal, the metal sheet is pressed against the first conductive member and the second conductive member at the rear end of the terminal, and the first conductive member and the second conductive member are electrically connected, such that the earphone plug is switched from the original first four-electrode mode (with dual channel signals, a microphone signal, and a ground signal) to the second three-electrode mode (with dual channel signals and a ground signal). In this way, the earphone plug of the invention is applicable to music players with three-electrode jacks and mobile phones with four-electrode jacks, and thus is an earphone plug with a dual-mode switching function, so as to provide ease of use for earphone products and meet the requirements of consumers. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.