Patent Publication Number: US-11665479-B2

Title: Sounding device

Description:
TECHNICAL FIELD 
     The disclosure relates to the field of electroacoustic conversion, and in particular, to a sounding device. 
     BACKGROUND 
     In order to adapt to miniaturization and multi-function development of various audio devices and information communication devices, sounding devices used in such devices are required to be more miniaturized correspondingly, so that the sounding devices fit with other surrounding elements more compactly. Especially with the development of thinness of mobile phones, increasingly high requirements are put forward on the quality of the sounding devices used therein. 
     In the related art, the sounding device includes a frame, and a vibration system and a magnetic circuit unit that are retained in the frame, the vibration system includes a diaphragm retained in the frame and a voice coil configured to drive the diaphragm to vibrate to produce sound, the voice coil includes a pair of first side edges and a pair of second side edges, the magnetic circuit unit includes an auxiliary magnetic body opposite to and spaced apart from the first side edge, and the auxiliary magnetic body includes a main body portion and an extension portion formed by extending from one side of the main body portion away from the first side edge. However, the extension portion is far away from the voice coil, resulting in low magnetic utilization. 
     Therefore, there is a need to provide a sounding device to solve the above problems. 
     SUMMARY 
     An objective of the disclosure is to provide a sounding device which can not only enable the auxiliary magnetic body to be more evenly around the voice coil, but also enable the voice coil to have a longer circumference with a same magnetic circuit area, thereby increasing a BL value. 
     A sounding device according to the disclosure includes a frame, and a vibration system and a magnetic circuit unit that are retained in the frame. The vibration system includes a diaphragm retained in the frame and a voice coil configured to drive the diaphragm to vibrate to produce sound. The voice coil includes a pair of first side edges and a pair of second side edges that are connected between the pair of first side edges. The magnetic circuit unit includes a yoke, a main magnetic body fixed to the yoke, and an auxiliary magnetic body surrounding the main magnetic body and forming a magnetic gap with the main magnetic body. The auxiliary magnetic body includes first auxiliary magnetic bodies opposite to and spaced apart from the pair of first side edges. Each of the first auxiliary magnetic bodies includes a main body portion and an extension portion formed by extending from one side of the main body portion away from one first side edge of the pair of first side edges. The main body portion is recessed toward side surfaces of the pair of first side edges to form grooves, the main magnetic body protrudes towards the grooves, and the pair of first side edges protrude towards the grooves, respectively. 
     As an improvement, a protruding shape of the main magnetic body and a protruding shape of each of the pair of first side edges match a shape of each of the grooves. 
     As an improvement, an elastic supporter connected to the vibration system is fixed to the frame, each of the first auxiliary magnetic bodies is located between the elastic supporter and one first side edge of the pair of first side edges, the elastic supporter comprises an auxiliary diaphragm, the auxiliary diaphragm is provided with an avoiding slot avoiding the extension portion, the auxiliary diaphragm comprises a first fixed portion fixed to the frame, a second fixed portion connected to the vibration system, and a suspension portion connecting the first fixed portion with the second fixed portion, and the avoiding slot extends from the second fixed portion to the suspension portion. 
     As an improvement, the elastic supporter further includes a flexible printed circuit board, and the flexible printed circuit board includes a retaining portion connected to the first fixed portion, a bonding portion fixed to the second fixed portion, and an elastic arm connecting the retaining portion with the bonding portion. An opening of the suspension portion faces towards the flexible printed circuit board, and an orthographic projection of the elastic arm on the auxiliary diaphragm is located within the suspension portion. 
     As an improvement, the flexible printed circuit board is located between the auxiliary diaphragm and the diaphragm. 
     As an improvement, a framework is connected to one side of the diaphragm facing towards the voice coil, and the voice coil and the elastic supporter each are connected to the framework. 
     As an improvement, the framework includes a framework main body fixed to the diaphragm, a first connection portion, and a second connection portion. An outer periphery of the framework main body extends away from the diaphragm to form the first connection portion, an inner periphery of the framework main body extends away from the diaphragm to form the second connection portion, the elastic supporter is connected to the first connection portion, and the voice coil is connected to the second connection portion. 
     As an improvement, notches are formed at the second connection portion, and the second connection portion are separated by notches into a plurality of isolation islands that is spaced apart from each other, and the voice coil is fixed to the plurality of isolation islands. 
     As an improvement, the magnetic circuit unit further includes an upper clamp plate covering the auxiliary magnetic body and fixed to the frame, and a pole plate covering the main magnetic body, wherein the upper clamp plate has a through hole where the pole plate is located. 
     Compared with the related art, in the sounding device according to the disclosure, the first side edge of the voice coil, the main magnetic body, and the first auxiliary magnetic body are designed in such a manner that the main body portion is recessed toward a side surface of the first side edge to form the groove and both the main magnetic body and the first side edge protrude towards the groove. In this way, the sounding device can not only enable the first auxiliary magnetic body to surround the voice coil more evenly, but also enable the voice coil to have a longer circumference with a same magnetic circuit area, thereby increasing BL value. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic exploded perspective view of a preferred embodiment of a sounding device according to the disclosure; 
         FIG.  2    is a schematic structural diagram of a flexible printed circuit board in the sounding device shown in  FIG.  1   ; 
         FIG.  3    is a schematic structural diagram of a framework in the sounding device shown in  FIG.  1   ; 
         FIG.  4    is a perspective view after assembly of the sounding device shown in  FIG.  1   ; 
         FIG.  5    is a sectional view of a sounding device along line A-A shown in  FIG.  4   ; 
         FIG.  6    is a sectional view of a sounding device along line B-B shown in  FIG.  4   ; 
         FIG.  7    is a schematic structural diagram of the sounding device shown in  FIG.  4    after removal of a yoke; and 
         FIG.  8    is a schematic structural diagram after assembly of an elastic supporter and a voice coil in the sounding device shown in  FIG.  1   . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The technical solutions in the embodiments of the disclosure will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the disclosure. The described embodiments are merely some of rather than all of the embodiments of the disclosure. All other embodiments acquired by those skilled in the art based on the embodiments of the disclosure shall fall within the protection scope of the disclosure. 
     As shown in  FIG.  1    to  FIG.  8   , the sounding device includes a frame  1 , and a vibration system  3  and a magnetic circuit unit  5  that are fixed to the frame  1 . The magnetic circuit unit  5  is configured to drive the vibration system  3  to vibrate to produce sound. 
     The vibration system  3  includes a diaphragm  31  retained in the frame  1 , and a voice coil  33  configured to drive the diaphragm  31  to vibrate to produce sound. The voice coil  33  is connected to an external circuit. After the voice coil  33  is energized, the voice coil  33  vibrates under a magnetic field of the magnetic circuit unit  5 . Meanwhile, the voice coil  33  drives the diaphragm  31  to vibrate to produce sound. 
     The voice coil  33  includes a pair of first side edges  331  and a pair of second side edges  333  connected between the first side edges  331 . As shown in  FIG.  1    and  FIG.  7   , the first side edge  331  is located in a direction of a major axis of the sounding device, and the second side edge  333  is located in a direction of a minor axis of the sounding device. 
     An elastic supporter  7  connected to the vibration system  3  is fixed to the frame  1 . 
     In an embodiment, a framework  9  is connected to one side of the diaphragm  31  facing towards the voice coil  33 , and the voice coil  33  and the elastic supporter  7  are connected to the framework  9 . The voice coil  33 , when vibrating, drives the diaphragm  31 , the framework  9 , and the elastic supporter  7  to vibrate together. 
     The framework  9  includes a framework main body  91  fixed to the diaphragm  31 , a first connection portion  93 , and a second connection portion  95 . An outer periphery of the framework main body  91  extends away from the diaphragm  31  to form the first connection portion  93 , and an inner periphery of the framework main body  91  extends away from the diaphragm  31  to form the second connection portion  95 . The elastic supporter  7  is connected to the first connection portion  93  to connect the elastic supporter  7  with the vibration system  3 . The voice coil  33  is connected to the second connection portion  95 . 
     It can be understood that, in other embodiments, no framework is provided. Correspondingly, the voice coil is fixed to the diaphragm, and one end of the elastic supporter away from the frame is fixed to one side of the voice coil away from the diaphragm, so as to connect the elastic supporter with the vibration system. 
     In an embodiment, multiple notches  951  are formed at the second connection portion  95 , the second connection portion  95  are separated by the multiple notches  951  into multiple isolation islands  953 , multiple isolation islands  953  are spaced apart from each other, and the voice coil  33  is fixed to the isolation islands  953 . 
     The elastic supporter  7  includes a flexible printed circuit board  71  and an auxiliary diaphragm  73  stacked along a vibrating direction of the diaphragm  31 . 
     As shown in  FIG.  5   , the flexible printed circuit board  71  is located between the auxiliary diaphragm  73  and the diaphragm  31 . 
     The flexible printed circuit board  71  includes a retaining portion  711  fixed to the frame  1 , a bonding portion  713  fixed to the first connection portion  93 , and an elastic arm  715  connecting the retaining portion  711  with the bonding portion  713 . 
     In an embodiment, one of the flexible printed circuit boards  71  further includes a pad portion  717  bending and extending from the bonding portion  713  towards the diaphragm  31 , and the pad portion  717  is provided with a pad electrically connected to the lead wire of the voice coil  33 . On the one hand, the flexible printed circuit board  71  has a function of supporting and fixing the vibration system  3 . On the other hand, the retaining portion  711  and the pad portion  717  of the flexible printed circuit board  71  are each provided with a pad. Conductive paths are arranged in the elastic arm  715  and the bonding portion  713  to be electrically connected to the pads on the retaining portion  711  and the pad portion  717 . The pad on the pad portion  717  is connected to the lead wire of the voice coil  33  to electrically connect the voice coil  33 . The pad on the retaining portion  711  is connected to an external circuit so that the voice coil  33  is electrically connected to the external circuit through the flexible printed circuit board  71 , and when the sounding device operates, an electric signal of the external circuit is transmitted to the voice coil  33  through the flexible printed circuit board  71 . 
     It can be understood that, in other embodiments, the flexible printed circuit board  71  can be provided with no pad portion. Correspondingly, the pad electrically connected to the lead wire of the voice coil  33  is arranged on the bonding portion. 
     The auxiliary diaphragm  73  includes a first fixed portion  731  fixed to one side of the retaining portion  711  away from the frame  1 , a second fixed portion  733  fixed to one side of the bonding portion  713  away from the first connection portion  93 , and a suspension portion  735  connecting the first fixed portion  731  with the second fixed portion  733 . An opening of the suspension portion  735  faces towards the flexible printed circuit board, and an orthographic projection of the elastic arm  715  on the auxiliary diaphragm  73  is located within the suspension portion  735 . That is, the first fixed portion  731  of the auxiliary diaphragm  73  is fixed to the frame  1  through the retaining portion  711 , and the second fixed portion  733  of the auxiliary diaphragm  73  is fixed to the first connection portion  353  through the bonding portion  713 . 
     It can be understood that, in other embodiments, the elastic supporter can also be designed in such a manner that the auxiliary diaphragm is located between the flexible printed circuit board and the diaphragm. Correspondingly, the opening of the suspension portion should faces away from the diaphragm. In an embodiment, the elastic supporter includes only the auxiliary diaphragm. 
     The magnetic circuit unit  5  includes a yoke  51 , a main magnetic body  53  fixed to the yoke  51 , an auxiliary magnetic body  55 , an upper clamp plate  57  covering the auxiliary magnetic body  55 , and a pole plate  59  covering the main magnetic body  53 . The auxiliary magnetic body  55  surrounds the main magnetic body  53  and forms a magnetic gap  5 A with the main magnetic body  53 . The upper clamp plate  57  is retained on the frame  1  to retain the magnetic circuit unit  5  on the frame  1 . The voice coil  33  is inserted in the magnetic gap  5 A, so that after the voice coil  33  is energized, the voice coil  33  can vibrate under the magnetic field of the magnetic circuit unit  5 . The upper clamp plate  57  has a through hole  571 , and the pole plate  59  is located in the through hole  571 . 
     In an embodiment, both the upper clamp plate  57  and the pole plate  59  are made of a magnetically conductive material, so as to enhance a magnetic flux within the magnetic gap  5 A. 
     The auxiliary magnetic body  55  includes a first auxiliary magnetic body  551  and a second auxiliary magnetic body  553  spaced apart from the second side edge  333 , the first auxiliary magnetic body  551  is opposite to and spaced apart from the first side edge  331  and located between the elastic supporter  7  and the first side edge  331 . As shown in  FIG.  8   , a space  8  is formed between the elastic supporter  7  and the first side edge  331  and configured to place the first auxiliary magnetic body  551 . 
     The first auxiliary magnetic body  551  includes a main body portion  555  and an extension portion  557  formed by extending from one side of the main body portion  555  away from the first side edge  331 . The auxiliary diaphragm  73  is provided with an avoiding slot  73 A configured to avoid the extension portion  557 , and the avoiding slot  73 A extends from the second fixed portion  733  to the suspension portion  735 . 
     The main body portion  555  is recessed toward a side surface of the first side edge  331  to form a groove  559 , and both the main magnetic body  53  and the first side edge  331  protrude towards the groove  559 . 
     In an embodiment, a protruding shape of the main magnetic body  53  and a protruding shape of the first side edge  331  match a shape of the groove  559 . As shown in  FIG.  7   , the groove  559  is in a shape of a triangle. It can be understood that the shape of the groove  559  is not limited thereto, which can also be, for example, a trapezoid, an arc or the like. 
     In an embodiment, the main magnetic body  53 , the first auxiliary magnetic body  551 , and the second auxiliary magnetic body  553  are all magnets. In other embodiments which include the main magnetic body  53 , the first auxiliary magnetic body  551  and the second auxiliary magnetic body  553 , two main magnetic bodies  53  can be two main magnets stacked along a vibrating direction of the diaphragm  31  and having opposite polarities. Correspondingly, the first auxiliary magnetic body  551  and the second auxiliary magnetic body  553  each can include two auxiliary magnets stacked along the vibrating direction of the diaphragm  31  and having opposite polarities, and in an embodiment, magnetic conduction plates made of a magnetically conductive material can be sandwiched between the two main magnets and between the two auxiliary magnets. 
     In other embodiments, the magnetic circuit unit  5  can be provided with no pole plate and no upper clamp plate. Correspondingly, the second auxiliary magnetic body is fixed to the frame to fix the magnetic circuit unit to the frame. 
     The above illustrates only some embodiments of the disclosure. It should be pointed out that those of ordinary skill in the art may also make improvements without departing from the ideas of the disclosure, all of which fall within the protection scope of the disclosure.