Patent Publication Number: US-9420377-B2

Title: Audio playback device

Description:
BACKGROUND 
     1. Field of Invention 
     The present invention relates to audio playback technology. More particularly, the present invention relates to an audio playback device. 
     2. Description of Related Art 
     Handheld electronic devices such as smartphones and tablet PCs become the most popular electronic products due to their light weight. Besides basic telephone communication ability, the handheld electronic devices are further equipped with wireless network communication ability to access information and perform communication conveniently. 
     Recently, the requirement of displaying multimedia files and games becomes higher. Audio playback device with good quality becomes a basic requirement of the handheld electronic devices. However, since the size of the handheld electronic devices is small, it is a great challenge to shrink the volume of the audio playback device without affecting its performance. 
     Accordingly, what is needed is an audio playback device to address the above issues. 
     SUMMARY 
     An aspect of the present invention is to provide an audio playback device. The audio playback device includes a magnetic module, an annular armature, a coil module and a diaphragm. The magnetic module includes a magnetic source and two yokes, wherein each of the two yokes is connected to one of two magnetic poles generated by the magnetic source, and the two yokes extend substantially in parallel to form a magnetic field therebetween. The annular armature includes a first arm, a second arm, a third arm and a fourth arm that form a hollow area, wherein the third arm and the fourth arm respectively connect the first arm to the second arm and at least part of the first arm is located in the magnetic field. The at least one coil module is wound on the second arm and generates two varying electro-magnetic poles corresponding to the third arm and the fourth arm respectively according to an alternating current signal, such that the annular armature vibrates according to a magnetic relation of the two varying electro-magnetic poles and the magnetic field. The diaphragm is connected to the annular armature through a driving rod to vibrate according to a vibration of the annular armature to generate a sound wave. 
     These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
         FIG. 1  is a 3 dimensional (3-D) perspective diagram of an audio playback device in an embodiment of the present invention; 
         FIG. 2  is a sectional side view of the audio playback device observed from direction A in  FIG. 1  in an embodiment of the present invention; 
         FIG. 3  is a 3-D diagram of the annular armature in an embodiment of the present invention; 
         FIG. 4  is a 3-D diagram of the audio playback device in  FIG. 1  in an embodiment of the present invention; 
         FIG. 5  is a 3-D diagram of the audio playback device in  FIG. 1  in an embodiment of the present invention; 
         FIG. 6  is a 3-D diagram of the magnetic module in an embodiment of the present invention; 
         FIG. 7  is a 3-D diagram of an annular armature, a first fixed wall and a second fixed wall in an embodiment of the present invention; 
         FIG. 8  is a 3-D perspective view of an audio playback device in an embodiment of the present invention; and 
         FIG. 9  is a cross-sectional side view of the audio playback device observed from direction E in  FIG. 8  in an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG. 1  is a 3 dimensional (3-D) perspective diagram of an audio playback device  1  in an embodiment of the present invention. The audio playback device  1  includes a magnetic module  10 , an annular armature  12 , coil modules  14 , a diaphragm  16  and a case  18 . The case  18  contains the magnetic module  10 , the annular armature  12  and the coil modules  14 . In order to clearly depict and introduce the elements contained in the case  18 , the case  18  is illustrated by dash lines. 
     The magnetic module  10  is discussed by using  FIG. 1  together with  FIG. 2 .  FIG. 2  is a sectional side view of the audio playback device  1  observed from direction A in  FIG. 1  in an embodiment of the present invention. 
     As illustrated in  FIG. 1  and  FIG. 2 , the magnetic module  10  includes a magnetic source  100  and two yokes  102 A and  102 B. In an embodiment, the magnetic source  100  is a permanent magnet to generate two magnetic poles including a north pole (N-pole) and a south pole (S-pole). In other embodiments, the magnetic source  100  can be other material or electro-magnetic equipment that is able to generate two steady magnetic poles. In the present embodiment, the magnetic source  100  is fixed to a sidewall  180  of the case  18  as illustrated in  FIG. 2 . 
     Each of the two yokes  102 A and  102 B is connected to one of the two magnetic poles of the magnetic source  100 . For example, the yoke  102 A is connected to the north pole and the yoke  102 B is connected to the south pole. In another embodiment, the yoke  102 A can be connected to the south pole and the yoke  102 B can be connected to the north pole. 
     In an embodiment, the magnetic source  100  and the yokes  102 A and  102 B can be implemented by a single horseshoe magnet. In another embodiment, the yokes may include magnetic-conducting material different from the material included in the magnetic source  100 . The magnetic-conducting material can be such as, but not limited to nickel, iron, cobalt, Gadolinium and an alloy or composite of at least one of the above. 
     The two yokes  102 A and  102 B extend substantially in parallel to extend the lines of the magnetic field of the two magnetic poles generated by the magnetic source  100  due to their magnetic-conducting ability. It is noted that the term ‘substantially’ means that the two yokes  102 A and  102 B are not necessarily to be completely in parallel to each other and a tolerable error may be presented. In an embodiment, the yoke  102 A includes a protrusion part  104 A and the yoke  102 B includes a protrusion part  104 B. The protrusion part  104 A and the protrusion part  104 B further guide the lines of the magnetic field toward the space between the two yokes  102 A and  102 B. A magnetic field is formed therebetween. 
     The annular armature  12  is discussed by using  FIG. 1  together with  FIG. 3 .  FIG. 3  is a 3-D diagram of the annular armature  12  in an embodiment of the present invention. 
     The annular armature  12  includes a first arm  120 , a second arm  122 , a third arm  124  and a fourth arm  126 . A hollow area  121  is formed, in which the hollow area  121  is surrounded by the first arm  120 , the second arm  122 , the third arm  124  and the fourth arm  126 . The third arm  124  and the fourth arm  126  respectively connect the first arm  120  to the second arm  122 . In different embodiments, the first arm  120 , the second arm  122 , the third arm  124  and the fourth arm  126  are either once-formed or are formed separately and connected to each other subsequently. The first arm  120 , the second arm  122 , the third arm  124  and the fourth arm  126  form a close loop without any gap formed thereon. For example, the first arm  120 , the second arm  122  and the third arm  124  can be once-formed and be further connected to the independently formed fourth arm  126  to form the close loop. 
     In different embodiments, the shape of the annular armature  12  is such as, but not limited to a square shape as illustrated in  FIG. 1 , a circular shape or any other symmetrical shapes. In different embodiment, the material of the annular armature  12  is such as, but not limited to silicon steel or other materials that can be magnetized. 
     In the present embodiment, at least part of the first arm  120  is located in the magnetic field formed between the yokes  102 A and  102 B illustrated in  FIG. 1 . 
     The coil modules  14  are discussed by using  FIG. 1  together with  FIG. 2  and  FIG. 3 . The coil modules  14  are wound on the annular armature  12 . In the present embodiment, the coil modules  14  are wound on the second arm  122 . In an embodiment, in order not to affect the operation of the annular armature  12 , the coil modules  14  do not contact the annular armature  12 . In the present embodiment, the coil modules  14  are fixed to the sidewall  182  of the case  18  as illustrated in  FIG. 2 , in which the sidewall  182  is opposite to the sidewall  180 . In other embodiments, the coil modules  14  can be fixed by other methods such that the coil modules  14  do not contact the annular armature  12 . In an embodiment, the coil modules  14  are formed by being wound on the second arm  122  of the once-formed annular armature  12 . In another embodiment, the coil modules  14  are formed first and the arms of the annular armature  12  are separately formed later. It is noted that the number of the coil modules  14  is not limited to two, as illustrated in  FIG. 2 . The number of the coil modules  14  can be adjusted according to the practical conditions. 
     The coil modules  14  generate two varying electro-magnetic poles corresponding to the third arm  124  and the fourth arm  126  respectively according to an alternating current signal. For example, when the alternating current in the coil modules  14  flows in direction I1 (clockwise) illustrated in  FIG. 2 , the direction of the magnetic field formed according to the alternating current is the direction B1 as illustrated in  FIG. 1 , according to Ampere&#39;s right hand rule. The north pole is generated at the location corresponding to the third arm  12  and the south pole is generated at the location corresponding to the fourth arm  126 . On the contrary, when the alternating current in the coil modules  14  flows in direction I2 (counterclockwise) illustrated in  FIG. 2 , the direction of the magnetic field formed according to the alternating current is the direction B2 as illustrated in  FIG. 1 , according to Ampere&#39;s right hand rule. The south pole is generated at the location corresponding to the third arm  12  and the north pole is generated at the location corresponding to the fourth arm  126 . 
     It is noted that, under the condition mentioned above, the magnetic field gradually switches from the one end of the first arm  120  connected to the third arm  124  and corresponding to one polarity to the other end of the first arm  120  connected to the fourth arm  126  and corresponding to the other polarity. Similarly, the magnetic field gradually switches from the one end of the second arm  122  connected to the third arm  124  and corresponding to one polarity to the other end of the second arm  122  connected to the fourth arm  126  and corresponding to the other polarity. 
     The two electro-magnetic poles generated on the third arm  124  and the fourth arm  126  by the coil modules  14  keep switching due to the variation of the alternating current signal. The magnetic relation between the first arm  120  and the magnetic field therefore keeps varying as well. 
     For example, the magnetic field is generated by the conducing arm  102 A with the north pole and the yoke  102 B with the south pole. When the north pole is generated on the third arm  124  and the south pole is generated on the fourth arm  126  according to the alternating current signal of the coil modules  14 , the end of the first arm  120  connected to the fourth arm  126  is attracted by the yoke  102 A and is rejected by the yoke  102 B. Hence, the end of the first arm  120  connected to the fourth arm  126  tends to rise. The end of the first arm  120  connected to the third arm  124  is rejected by the yoke  102 A and is attracted by the yoke  102 B. Hence, the end of the first arm  120  connected to the third arm  124  tends to fall. 
     On the contrary, when the north pole is generated on the fourth arm  126  and the south pole is generated on the third arm  124  according to the alternating current signal of the coil modules  14 , the end of the first arm  120  connected to the fourth arm  126  tends to fall, and the end of the first arm  120  connected to the third arm  124  tends to rise. 
     Due to the quick-varying alternating current signal, the annular armature  12  keeps vibrating. In an embodiment, when the magnetic forces applied to the annular armature  12  are symmetry, the annular armature  12  vibrates around an axis C extending from the central area of the first arm  120  to the central area of the second arm  122 . 
     The diaphragm  16  is connected to the annular armature  12  through a driving rod  160 . In the present embodiment, the diaphragm  16  is disposed corresponding to the opening  184  of the case  18  and is suspended at an edge of the opening  184 . The diaphragm  16  can be suspended at the edge of the opening by using such as, but not limited to an elastic connection means  162 . It is noted that the shape of each of the diaphragm  16  and the corresponding opening  184  are not necessarily to be a square shape and can be adjusted in other embodiments according to the practical conditions. 
     When the annular armature  12  vibrates according to the alternating current signal in the coil modules  14 , the diaphragm  16  vibrates according to the vibration of the annular armature  12  to generate a sound wave. In the present embodiment, as illustrated in  FIG. 1 , the diaphragm  16  is connected to the fourth arm  126  of the annular armature  12  through the driving rod  160  such that the diaphragm  16  is able to vibrate to accomplish larger amplitude. In other embodiments, the driving rod  160  is not necessarily to be disposed on the location illustrated in  FIG. 1  and can be disposed in other locations of the annular armature  12  where the driving rod  160  can vibrate accordingly. 
     It is noted that in order to prevent the vibrating annular armature  12  crashes to the yokes  102 A and  102 B, the audio playback device  1  may selectively include crash-proof pads  106 A and  106 B disposed on the yokes  102 A and  102 B as illustrated in  FIG. 1 . In other embodiments, the crash-proof pads  106 A and  106 B can be disposed on the front end of the protrusion parts  104 A and  104 B. In an embodiment, the crash-proof pads  106 A and  106 B includes a soft or elastic material. Moreover, the distance between the two crash-proof pads  106 A and  106 B and the annular armature  12  is smaller than that between the two yokes  102 A and  102 B and the annular armature  12 . As a result, the crash-proof pads  106 A and  106 B provide the protection mechanism when the annular armature  12  vibrates. 
     Consequently, the coil modules  14  generate varying electro-magnetic poles on the annular armature  12  according to the alternating current signal transmitted from such as a driving circuit (not illustrated). The annular armature  12  vibrates according to the magnetic relation of the varying electro-magnetic poles and the magnetic field established by the magnetic module  10 . The diaphragm  16  further vibrates according to the driving rod  160  connected to the vibrating annular armature  12 . Since the magnetic resistance of the annular armature  12  is small, a high vibration efficiency is obtained according to the magnetic force even when the size of the annular armature  12  is small. Further, different sound waves are generated from the diaphragm  16  according to various amplitudes and frequencies of the alternating current signal. The audio playback mechanism can be accomplished. 
       FIG. 4  is a 3-D diagram of the audio playback device  1  in  FIG. 1  in an embodiment of the present invention. As illustrated in  FIG. 4 , the case  18  of the audio playback device  1  contains and caps the magnetic module  10 , the annular armature  12  and the coil modules  14 . Only the diaphragm  16  suspended by the connection means  162  at the edge of the opening  184  is exposed. 
       FIG. 5  is a 3-D diagram of the audio playback device  5  in  FIG. 1  in an embodiment of the present invention. In the present embodiment, the audio playback device  5  includes all the components illustrated in  FIG. 1  to  FIG. 4 . Moreover, the audio playback device  5  includes a cap  50  to cover the surface corresponding to the opening  184  (not illustrated in  FIG. 5 ) to provide a protection mechanism. In the present embodiment, in order not to block the sound wave generated by the components disposed inside, the cap  50  includes sound holes  52  formed thereon such that the sound wave can be transmitted outside of the audio playback device  5  through the sound holes  52 . 
       FIG. 6  is a 3-D diagram of the magnetic module  60  in an embodiment of the present invention. In the present embodiment, the magnetic module  60  includes a magnetic source  600  and two yokes  602 A and  602 B. The magnetic source  600  is the same as the magnetic source  100  illustrated in  FIG. 2  and generates two magnetic poles. 
     Each of the yokes  602 A and  602 B is corresponding to one of the two magnetic poles to extend the lines of the magnetic field from the magnetic source  600 . In the present embodiment, the yoke  602 A includes two protrusion parts  604 A and  606 A. The yoke  602 B includes two protrusion parts  604 B and  606 B. The protrusion parts  604 A and  604 B are opposite to each other and the protrusion parts  606 A and  606 B are opposite to each other. The protrusion parts  604 A,  604 B,  606 A and  606 B guide the lines of the magnetic field more concentratedly to the space between the yokes  602 A and  602 B to form a stronger magnetic field. 
       FIG. 7  is a 3-D diagram of an annular armature  70 , a first fixed wall  72  and a second fixed wall  74  in an embodiment of the present invention. The annular armature  70  is the same as the annular armature  12  illustrated in  FIG. 3  and includes a first arm  700 , a second arm  702 , a third arm  704  and a fourth arm  706 . The first arm  700 , the second arm  702 , the third arm  704  and the fourth arm  706  are respectively formed and subsequently connected to form a close loop. 
     In the present embodiment, the first arm  700  and the second arm  702  include a first protrusion part  76  and a second protrusion part  78  respectively. The first protrusion part  76  and the second protrusion part  78  extend to be vertically embedded to the first fixed wall  72  and the second fixed wall  74  respectively. In an embodiment, the first protrusion part  76  is formed on a central area of the first arm  700 . The second protrusion part  78  is formed on a central area of the second arm  702 . As a result, when the annular armature  70  vibrates according to the magnetic force as described in the previous embodiments, the annular armature  70  vibrates around the axis D formed between the first protrusion part  76  and the second protrusion part  78 . 
     The first fixed wall  72  and the second fixed wall  74  are discussed in detail in the subsequent embodiment. 
       FIG. 8  is a 3-D perspective view of an audio playback device  8  in an embodiment of the present invention.  FIG. 9  is a cross-sectional side view of the audio playback device  8  observed from direction E in  FIG. 8  in an embodiment of the present invention. 
     The audio playback device  8  includes similar components as those of the audio playback device  1  illustrated in  FIG. 1  and  FIG. 2 , e.g. the coil modules  14 , the diaphragm  16  and the case  18 . These components in  FIG. 8  substantially have the same structures and functions as those illustrated in  FIG. 1  and  FIG. 2 . Hence, no more detail is discussed herein. However, the audio playback device  8  includes the magnetic module  60  illustrated in  FIG. 6  and the annular armature  70 , the first fixed wall  72  and the second fixed wall  74  illustrated in  FIG. 7 . 
     In the present embodiment, the first fixed wall  72  and the second fixed wall  74  are substantially in parallel. It is noted that the term ‘substantially’ means that the first fixed wall  72  and the second fixed wall  74  are not necessarily to be completely in parallel to each other and a tolerable error may be presented. The first fixed wall  72  is connected to the case  18 , e.g. the sidewall  182  of the case  18 . In the present embodiment, the second fixed wall  74  is connected to the yokes  602 A and  602 B. Therefore, the first fixed wall  72  and the second fixed wall  74  provides a fixing mechanism for the annular armature  70 . The vibration of the annular armature  70  generated according to the alternating current signal in the coil modules  14  can be transmitted more thoroughly to the diaphragm  16  through the driving rod  160 . The loss of energy due to the unstable annular armature  70  is prevented. 
     It is noted that the design of the magnetic module  60 , the annular armature  70 , the first fixed wall  72  and the second fixed wall  74  can be applied to the embodiments illustrated in  FIG. 1  and  FIG. 2  as well, and is not limited to the embodiments illustrated in  FIG. 7  and  FIG. 8 . 
     Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.