Patent Publication Number: US-2022217471-A1

Title: Speaker unit with dual diaphragms and dual coils

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwanese application no. 110100295, filed on Jan. 5, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND 
     Technical Field 
     The disclosure relates to a speaker unit; in particular, the disclosure relates to a speaker unit with dual diaphragms and dual coils. 
     Description of Related Art 
     With continuous technological advancement, personal electronic products are all trending toward being lightweight and miniaturized. Smart phones, tablet computers, notebook computers, or the like have become indispensable in people&#39;s daily life. For any of the above-mentioned electronic products, earphones have become necessary accessories for users to listen to audio information provided by the electronic products without disturbing others. Earphones provide better sound transmission to listeners, so that the listeners clearly hear and understand the content of the sound, rather than unclear sound resulting from sound transmission in the air. With earphones, the sound transmission will not be affected especially when the users are moving, for example, during exercise, driving, or intense activities or are in noisy environments. In addition, for making calls with the electronic products, a headset with a microphone is also a common accessory. 
     Besides, with the technological advancement, wireless earphones that rid the users of wires are also more and more popular with the users. In addition to the use of wireless technology, noise cancelation is also of an important consideration for many users when purchasing earphones. In the current active noise-canceling technology, a microphone configured to collect noise is disposed in the earphones, and the noise collected by the microphone is converted into a digital signal, inverted, mixed with an original audio signal to be played, and then played by a speaker unit in the earphones, so as to offset an environmental noise and achieve noise cancelation. However, the audio mixed with the inverted noise signal is distorted when played through a single speaker unit, resulting in a lowered desire of purchase of the users. 
     SUMMARY 
     The disclosure provides a speaker unit, which increases adversely affected sound quality caused by noise cancelation. 
     According to an embodiment of the disclosure, the speaker unit with dual diaphragms and dual coils includes a casing, a first magnetic element, a first vibration system, a second magnetic element, and a second vibration system. The casing has a chamber. The first magnetic member is disposed in the chamber of the casing. The first vibration system includes a first diaphragm and a first coil. The first diaphragm is fixed on the casing and located in the chamber. The first diaphragm has a ring shape. The first coil is fixed on the first diaphragm and located beside the first magnetic member. The second magnetic member is disposed in the chamber of the casing. An orthogonal projection of the second magnetic member on an inner bottom surface of the casing is completely located in an orthogonal projection of a central opening of the first diaphragm on the inner bottom surface. The second vibration system includes a second diaphragm and a second coil. The second diaphragm is fixed on the casing and located in the chamber. The second coil is fixed on the second diaphragm and located beside the second magnetic element. 
     In an embodiment of the disclosure, the speaker unit with dual diaphragms and dual coils further includes a microphone. The microphone is disposed in the casing. 
     In an embodiment of the disclosure, the microphone is disposed on an outer top surface of the casing. The first magnetic element and the second magnetic element are located between the outer top surface and the inner bottom surface. 
     In an embodiment of the disclosure, the speaker unit with dual diaphragms and dual coils further includes a printed circuit board and a flexible circuit board. The printed circuit board is disposed on an outer bottom surface of the casing. The flexible circuit board is electrically connected to the microphone and the printed circuit board. The inner bottom surface is located between the outer top surface and the outer bottom surface. 
     In an embodiment of the disclosure, the first magnetic element and the second magnetic element are stacked on the inner bottom surface. The first magnetic element is located between the second magnetic element and the inner bottom surface. 
     In an embodiment of the disclosure, an inner edge of the first diaphragm is fixed on the first magnetic element. An outer edge of the first diaphragm is fixed on the casing. 
     In an embodiment of the disclosure, the speaker unit with dual diaphragms and dual coils further includes a separator. The separator is disposed in the chamber of the casing to separate the chamber into a first audio chamber and a second audio chamber. The first diaphragm is located in the first audio chamber. The second diaphragm is located in the second audio chamber. 
     In an embodiment of the disclosure, the casing also has a first audio hole and a second audio hole. The first audio chamber is connected to an outside through the first audio hole. The second audio chamber is connected to the outside through the second audio hole. 
     In an embodiment of the disclosure, the speaker unit with dual diaphragms and dual coils further includes a first tuning element and a second tuning element. The first tuning element covers the first audio hole. The second tuning element covers the second audio hole. 
     In an embodiment of the disclosure, the speaker unit with dual diaphragms and dual coils further includes a driving circuit. The driving circuit includes an audio positive end, an audio negative end, a noise-canceling positive end, a noise-canceling negative end, a microphone positive end, a microphone negative end, and an audio input end. The audio positive end and the audio negative end are electrically connected to the second coil. The noise-canceling positive end and the noise-canceling negative end are electrically connected to the first coil. The microphone positive end and the microphone negative end are electrically connected to the microphone. The audio positive end and the audio negative end are electrically connected to the audio input end. The audio input end is electrically connected to an external audio source. The noise-canceling positive end and the noise-canceling negative end are electrically connected to the microphone. 
     In an embodiment of the disclosure, the audio positive end and the audio negative end are electrically isolated from the microphone positive end and the microphone negative end. The noise-canceling positive end and the noise-canceling negative end are electrically isolated from the audio input end. 
     Based on the foregoing, the speaker unit with dual diaphragms and dual coils of the disclosure includes two vibration systems, respectively playing a target audio and an inverted noise audio. Therefore, fidelity of the sound is increased and noise cancelation is achieved. 
     To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
         FIG. 1  is a three-dimensional cross-sectional view of a speaker unit with dual diaphragms and dual coils according to an embodiment of the disclosure. 
         FIG. 2  is an exploded view of the speaker unit with dual diaphragms and dual coils of  FIG. 1 . 
         FIG. 3  is an exploded view of the speaker unit with dual diaphragms and dual coils of  FIG. 1  from another view angle. 
         FIG. 4  is a schematic cross-sectional view of the speaker unit with dual diaphragms and dual coils of  FIG. 1  being applied to an earphone. 
         FIG. 5  is a schematic block diagram of the speaker unit with dual diaphragms and dual coils of  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  is a three-dimensional cross-sectional view of a speaker unit with dual diaphragms and dual coils according to an embodiment of the disclosure. With reference to  FIG. 1 , according to an embodiment of the disclosure, a speaker unit with dual diaphragms and dual coils  100  includes a casing  110 , a first magnetic element  120 , a first vibration system  130 , a second magnetic element  140 , and a second vibration system  150 . The casing  110  has a chamber  112 . The first magnetic element  120  is disposed in the chamber  112  of the casing  110 . The first vibration system  130  includes a first diaphragm  132  and a first coil  134 . The first diaphragm  132  is fixed on the casing  110  and located in the chamber  112 . The first diaphragm  132  has a ring shape. The first coil  134  is fixed on the first diaphragm  132  and located beside the first magnetic element  120 . That is, through the cooperation between the first coil  134  and the first magnetic element  120 , the first coil  134  drives the first diaphragm  132  to vibrate and emit a sound. 
     The second magnetic element  140  is disposed in the chamber  112  of the casing  110 . An orthogonal projection of the second magnetic element  140  on an inner bottom surface S 12  of the casing  110  is completely located in an orthogonal projection of a central opening P 12  of the first diaphragm  132  on the inner bottom surface S 12 . That is, in a top view of  FIG. 1 , the second magnetic element  140  is completely located in the central opening P 12  of the first diaphragm  132 . Besides, in a side view of  FIG. 1 , the second magnetic element  140  of the embodiment penetrates the central opening P 12  of the first diaphragm  132 . In other embodiments, it is also possible that the second magnetic element does not penetrate the central opening of the first diaphragm, which is not limited by the disclosure. 
     The second vibration system  150  includes a second diaphragm  152  and a second coil  154 . The second diaphragm  152  is fixed on the casing  110  and located in the chamber  112 . The second coil  154  is fixed on the second diaphragm  152  and located beside the second magnetic element  140 . That is, through the cooperation between the second coil  154  and the second magnetic element  140 , the second coil  154  drives the second diaphragm  152  to vibrate and emit a sound. 
     In this embodiment, the first diaphragm  132  and the second diaphragm  152  independent of each other are included, which may respectively play audios from different sources. For example, the first diaphragm  132   a  may play a noise audio obtained from an environmental noise being converted into a digital signal and inverted. On the other hand, the second diaphragm  152  may play a target audio input from an external audio source, such as music, voice content, and the like. Therefore, the second diaphragm  152  plays the audio input from the external audio source with high fidelity, and the inverted noise audio played by the first diaphragm  132  also offsets the environmental noise to achieve noise cancelation. 
     Besides, since the noise sensible by a user is mainly in a low frequency portion, thus noise cancelation is achieved as long as the low-frequency noise is offset. When the inverted noise audio is played with the first diaphragm  132 , noise cancelation is not much affected even though a frequency response of the first diaphragm  132  is lower in a high frequency portion due to the presence of the central opening P 12 . In addition, since the central opening P 12  accommodates the second magnetic element  140 , the size of the speaker unit with dual diaphragms and dual coils  100  will not be greatly increased due to the two diaphragms and the two magnetic elements. 
       FIG. 2  is an exploded view of the speaker unit with dual diaphragms and dual coils of  FIG. 1 . With reference to  FIG. 1  and  FIG. 2 , in this embodiment, the speaker unit with dual diaphragms and dual coils  100  further includes a microphone  160  disposed on the casing  110 . For example, the microphone  160  may collect the environmental noise. After the environmental noise collected by the microphone  160  is converted into a digital signal and inverted, the obtained noise audio may be played by the first diaphragm  132 . The microphone  160  of this embodiment is disposed on an outer top surface S 14  of the casing  110 . The first magnetic element  120  and the second magnetic element  140  are located between the outer top surface S 14  and the inner bottom surface S 12 . For example, the casing  110  includes a first element  110 A. The first element  110 A has the outer top surface S 14 , and the microphone  160  is disposed on the outer top surface S 14  of the first element  110 A. The first element  110 A, for example, has a hole for the sound emitted by the second diaphragm  152  to pass through and be transmitted to an eardrum of the user. Besides, the first element  110 A may provide a supporting structure for the microphone  160  to be elevated above the outer top surface S 14  to prevent the microphone  160  from covering the hole. 
       FIG. 3  is an exploded view of the speaker unit with dual diaphragms and dual coils of  FIG. 1  from another view angle. With reference to  FIG. 1  to  FIG. 3 , in this embodiment, the speaker unit with dual diaphragms and dual coils  100  further includes a printed circuit board  170  and a flexible circuit board  180 . The printed circuit board  170  is disposed on an outer bottom surface S 16  of the casing  110 . For example, the casing  110  also includes a third element  110 C. The third element  110 C has the outer bottom surface S 16 , and the printed circuit board  170  is disposed on the outer bottom surface S 16  of the third element  110 C. The flexible circuit board  180  is electrically connected to the microphone  160  and the printed circuit board  170 . The inner bottom surface S 12  is located between the outer top surface S 14  and the outer bottom surface S 16 . In other words, the microphone  160  and the printed circuit board  170  are respectively located on upper and lower sides of the casing  110 . Therefore, when the speaker unit with dual diaphragms and dual coils  100  is applied to an earphone worn in an ear canal of the user, the microphone  160  is closer to the eardrum of the user than other components, and further collects noise received closer to the eardrum of the user, increasing noise cancelation. The flexible circuit board  180  may transmit signals between the printed circuit board  170  and the microphone  160 , and the flexible circuit board  180  may also transmit signals between the printed circuit board  170  and external elements. 
     In this embodiment, the first magnetic element  120  and the second magnetic element  140  are stacked on the inner bottom surface S 12 . The first magnetic element  120  is located between the second magnetic element  140  and the inner bottom surface S 12 . With such an architecture, space required for disposing the first magnetic element  120  and the second magnetic element  140  may be saved, such that the speaker unit with dual diaphragms and dual coils  100  has a compact size. The first magnetic element  120  of the embodiment includes, for example, a permanent magnetic element  122  and a magnetic induction element  124 , and the magnetic induction element  124  is located between the permanent magnetic element  122  and the first diaphragm  132 . The second magnetic element  140  of this embodiment includes, for example, a permanent magnetic element  142  and a magnetic induction element  144 , and the magnetic induction element  144  is located between the permanent magnetic element  142  and the second diaphragm  152 . 
     In this embodiment, an inner edge of the first diaphragm  132  is fixed on the first magnetic element  120 . An outer edge of the first diaphragm  132  is fixed on the casing  110 . The inner edge of the first diaphragm  132  is namely an edge of the central opening P 12 . For example, the inner edge and the outer edge of the first diaphragm  132  respectively have fixing rings, and the two fixing rings are respectively fixed on the first magnetic element  120  and the casing  110 . With the fixing rings, the first diaphragm  132  is ensured to be less susceptible to deformation and damage. 
     In this embodiment, the speaker unit with dual diaphragms and dual coils  100  further includes a separator  190 , which is disposed in the chamber  112  of the casing  110  to separate the chamber  112  into a first audio chamber  112 A and a second audio chamber  112 B. The first diaphragm  132  is located in the first audio chamber  112 A. The second diaphragm  152  is located in the second audio chamber  112 B. For example, the separator  190  is disposed on the first magnetic element  120 . The casing  110  also includes a second element  110 B. The separator  190 , the second element  110 B, the third element  110 C, and the first magnetic element  120  together define the first audio chamber  112 A. The separator  190  and the second element  110 B are both located above the first diaphragm  132 . The second element  110 B, for example, has a hole for the sound emitted by the first diaphragm  132  to pass through and be transmitted to the eardrum of the user. 
     In this embodiment, the casing  110  also has a first audio hole P 14  and a second audio hole P 16 . The first audio chamber  112 A is connected to the outside through the first audio hole P 14 . The second audio chamber  112 B is connected to the outside through the second audio hole P 16 . Specifically, the first audio hole P 14  and the second audio hole P 16  are respectively located behind the first diaphragm  132  and the second diaphragm  152 , so that air can pass through when the first diaphragm  132  and the second diaphragm  152  are vibrating, preventing influences on vibration of the first diaphragm  132  and the second diaphragm  152 . The first audio hole P 14  of this embodiment is located on the third element  110 C, for example. The second audio hole P 16  of this embodiment, for example, passes through the first magnetic element  120 , the second magnetic element  140 , and the third element  110 C. 
     In this embodiment, the speaker unit with dual diaphragms and dual coils  100  further includes a first tuning element  192  and a second tuning element  194 . The first tuning element  192  covers the first audio hole P 14 . The second tuning element  194  covers the second audio hole P 16 . The materials of the first tuning element  192  and the second tuning element  194  includes, for example, non-woven fabric or other appropriate materials. 
       FIG. 4  is a schematic cross-sectional view of the speaker unit with dual diaphragms and dual coils of  FIG. 1  being applied to an earphone. With reference to  FIG. 1  and  FIG. 4 , when applied to an earphone, the speaker unit with dual diaphragms and dual coils  100  of this embodiment may be mounted in a molded casing  10 . The speaker unit with dual diaphragms and dual coils  100  and the molded casing  10  may be assembled through dispensing a glue at the junction between the two. The appearance of the molded casing  10  may vary depending on design requirements, and an ear pad (not shown) may be mounted on one side of the molded casing  10  for comfort in use. 
       FIG. 5  is a schematic block diagram of the speaker unit with dual diaphragms and dual coils of  FIG. 1 . With reference to  FIG. 1  and  FIG. 5 , in this embodiment, the speaker unit with dual diaphragms and dual coils  100  also includes a driving circuit C 10 . For example, the driving circuit C 10  may be fabricated on the printed circuit board  170  and the flexible circuit board  180 . The driving circuit C 10  includes an audio positive end C 10 A, an audio negative end C 10 B, a noise-canceling positive end C 10 C, a noise-canceling negative end C 10 D, a microphone positive end C 10 E, a microphone negative end C 10 F, and an audio input end C 10 G. The audio positive end C 10 A and the audio negative end C 10 B are electrically connected to the second coil  154 . The noise-canceling positive end C 10 C and the noise-canceling negative end C 10 D are electrically connected to the first coil  134 . The microphone positive end C 10 E and the microphone negative end C 10 F are electrically connected to the microphone  160 . The audio positive end C 10 A and the audio negative end C 10 B are electrically connected to the audio input end C 10 G. The audio input end C 10 G is electrically connected to an external audio source  50 . The noise-canceling positive end C 10 C and the noise-canceling negative end C 10 D are electrically connected to the microphone  160 . 
     The target audio provided by the external audio source  50  may be transmitted through the driving circuit C 10  to the second coil  154  to thereby drive the second diaphragm  152  to vibrate and emit a sound. The environmental noise collected by the microphone  160  may be converted into a digital signal and inverted by the driving circuit C 10 . Then, the obtained noise audio is transmitted to the first coil  134  to thereby drive the first diaphragm  132  to vibrate and emit a sound. 
     In this embodiment, the audio positive end C 10 A and the audio negative end C 10 B are electrically isolated from the microphone positive end C 10 E and the microphone negative end C 10 F. The noise-canceling positive end C 10 C and the noise-canceling negative end C 10 D are electrically isolated from the audio input end C 10 G. That is, the target audio provided by the external audio source  50  will not be transmitted to the first coil  134  to be emitted by the first diaphragm  132  through vibration. In addition, after the environmental noise collected by the microphone  160  is inverted, the obtained noise audio will not be transmitted to the second coil  154  to be emitted by the second diaphragm  152  through vibration. Therefore, interference is prevented between the two. 
     In summary of the foregoing, in the speaker unit with dual diaphragms and dual coils of the disclosure, the two vibration systems respectively play different audios. For example, one vibration system plays the target audio, and another vibration system plays the inverted noise audio. Therefore, the user can listen to the target audio with high fidelity when the environmental noise is offset by the inverted noise audio to achieve noise cancelation. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.