Patent Publication Number: US-11381916-B2

Title: Speaker system of personal mobility device and vehicle speaker system using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims under 35 U.S.C. § 119 the benefit of Korean Patent Application No. 10-2020-0045450, filed on Apr. 14, 2020 in the Korean Intellectual Property Office, the entire contents of which are incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to a speaker system of a personal mobility device and a vehicle speaker system using the same, more particularly, to the speaker system of the personal mobility device in which when the personal mobility device is mounted in a vehicle, a speaker installed on the personal mobility device generates a virtual engine sound and assists a vehicle speaker, and a vehicle speaker system using the same. 
     2. Description of the Related Art 
     In general, a personal mobility device (PMD) travels at an average speed of around 25 Km/h using the power of a motor driven by a battery, and a high-end personal mobility device may travel at a high speed of 40 to 60 Km/h. 
     However, due to a low-noise motor, it is difficult for a pedestrian to early recognize that a personal mobility device traveling at a high speed approaches the pedestrian. 
     Therefore, in recent years, in addition to electric vehicles (EVs), a virtual engine sound system (VESS) that generates a virtual engine sound is required to be installed in a personal mobility device driven by a motor in order to prevent pedestrian accidents. 
     An electric vehicle utilizes an electric drive motor operated by electric energy stored in a battery to provide power to the vehicle, and uses a number of parts such as a battery and an electric drive motor, and thus the size, capacity, and position of a subwoofer occupying the largest volume in the vehicle may be narrowed, and speaker performance may be degraded. 
     SUMMARY 
     It is an aspect of the disclosure to provide a speaker system of a personal mobility device in which when the personal mobility device is mounted in a vehicle, a speaker installed on the personal mobility device generates a virtual engine sound and assists a vehicle speaker, and a vehicle speaker system using the same. 
     Additional aspects of the disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosure. 
     In accordance with an aspect of the disclosure, a speaker system of a personal mobility device includes a main body configured to generate power with a battery, a steering unit connected to the main body to regulate a driving direction and in which a speaker is installed, wheels installed on the main body and the steering unit and rotated by power generated from the main body, and a controller configured to control the speaker, wherein the speaker generates a virtual engine sound when driving. 
     The steering unit may include a rod part coupled to the handle part, and an acoustic transmission portion to transmit acoustic energy generated from the speaker may be provided inside the rod part. 
     One or more frequency adjusters protruding toward an inner center of the rod part may be provided in the acoustic transmission portion. 
     The one or more frequency adjusters may include a first frequency adjuster, a second frequency adjuster, and a third frequency adjuster, which are formed along an inner circumferential surface of the rod part, and a length between the first frequency adjuster and the second frequency adjuster and a length between the second frequency adjuster and the third frequency adjuster may be different from each other. 
     The speaker may be installed at one end of the rod part, and the steering unit may include an accommodating part to accommodate the rod part and the speaker. 
     In accordance with another aspect of the disclosure, a vehicle speaker system uses a speaker system of a personal mobility device, wherein the speaker system of the personal mobility device is controlled by a vehicle controller installed in a vehicle when mounted in the vehicle. 
     A main body, a steering unit, wheels, and a controller may be mounted in an accommodating part provided in the vehicle, and the accommodating part may be provided in the form of an encloser to utilize acoustic energy transmitted through a speaker as a low-pitched frequency. 
     The battery and the speaker may be electrically connected to the vehicle through a connection part provided in the vehicle, and the vehicle controller installed in the vehicle may control the speaker through the connection part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects of the disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a schematic diagram illustrating a speaker system of a personal mobility device according to an embodiment of the disclosure and a vehicle speaker system using the same; 
         FIG. 2  illustrates the speaker system of the personal mobility device according to an embodiment of the disclosure; 
         FIG. 3  illustrates a rod part of the speaker system of the personal mobility device according to an embodiment of the disclosure; 
         FIG. 4  illustrates sound wave forms by the rod part illustrated in  FIG. 3 ; 
         FIG. 5  illustrates a rod part of another form according to an embodiment of the disclosure; 
         FIG. 6  illustrates sound wave forms by the rod part illustrated in  FIG. 5 ; and 
         FIG. 7  illustrates that the speaker system of the personal mobility device according to an embodiment of the disclosure is mounted on a vehicle. 
     
    
    
     DETAILED DESCRIPTION 
     It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Throughout the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, the terms “unit”, “-er”, “-or”, and “module” described in the specification mean units for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof. 
     Further, the control logic of the present disclosure may be embodied as non-transitory computer readable media on a computer readable medium containing executable program instructions executed by a processor, controller or the like. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards and optical data storage devices. The computer readable medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion, e.g., by a telematics server or a Controller Area Network (CAN). 
     Hereinafter embodiments of the disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below are provided by way of example so that those skilled in the art will be able to fully understand the spirit of the disclosure. The disclosure is not limited to the embodiments described below, but may be embodied in other forms. In order to clearly explain the disclosure, parts not related to the description are omitted from the drawings, and the width, length, thickness, etc. of the components may be exaggerated for convenience. 
     Hereinafter, a speaker system of a personal mobility device and a vehicle speaker system using the same according to an embodiment of the disclosure will be described with reference to  FIGS. 1 to 7 . 
       FIG. 1  is a schematic diagram illustrating a speaker system of a personal mobility device according to an embodiment of the disclosure and a vehicle speaker system using the same, and  FIG. 2  illustrates the speaker system of the personal mobility device according to an embodiment of the disclosure. 
       FIG. 3  illustrates a rod part of the speaker system of the personal mobility device according to an embodiment of the disclosure, and  FIG. 4  illustrates sound wave forms by the rod part illustrated in  FIG. 3 . 
       FIG. 5  illustrates a rod part of another form according to an embodiment of the disclosure, and  FIG. 6  illustrates sound wave forms by the rod part illustrated in  FIG. 5 . 
       FIG. 7  illustrates that the speaker system of the personal mobility device according to an embodiment of the disclosure is mounted on a vehicle. 
     As illustrated in  FIGS. 1 to 7 , a speaker system  100  of a personal mobility device according to an embodiment of the disclosure includes a main body  110 , a steering unit  120 , wheels  130 , and a controller  140 . 
     The main body  110  is used as a footrest on which a user rides and generates power by a battery  111 . The main body  110  drives a driver  112 , which is a motor, using electric power generated by the battery  111 . 
     The main body  110  may have a predetermined strength to support a weight of the user and may be provided in the form of a case in which a space is formed to accommodate the battery  111 , the controller  140 , and the like. 
     The steering unit  120  is connected to the main body  110  to regulate a driving direction. The steering unit  120  includes a handle part  121 , a rod part  122 , a speaker  123 , an accommodating part  124 , and an opening/closing part  125 . 
     The handle part  121  is provided on an upper side of the steering unit  120  so that the steering unit  120  may be controlled by the user, and may have a structure that is folded when mounted on the vehicle  200  by being connected to the rod part  122  through a hinge structure. 
     The rod part  122  is connected to the handle part  121  and is elongated or contracted by a predetermined length to assist the driving of the user holding the handle part  121 . The rod part  122  is provided with an acoustic transmission portion  122   a  therein to transmit acoustic energy generated from the speaker  123 . The rod part  122  may be provided in a telescopic form in which a plurality of tubes is overlapped to reduce a length of the accommodating part  124 . 
     The speaker  123  is installed at a lower end of the rod part  122  to supply acoustic energy to the acoustic transmission portion  122   a  and is controlled by the controller  140 . The speaker  123  generates a virtual engine sound when driving, and output of the virtual engine sound may be controlled by the controller  140 . 
     The speaker  123  may be controlled by the controller  140  installed in the personal mobility device when not mounted in the vehicle  200 , and may be controlled by a vehicle controller  230  installed in the vehicle  200  when mounted in the vehicle  200 . 
     The accommodating part  124  is connected to the rod part  122  at one end thereof to prevent the elongated or contracted rod part  122  from being separated, and is provided in a hollow form so that the rod part  122  and the speaker  123  are accommodated in the accommodating part  124 . 
     The opening/closing part  125  is provided at the opposite side of the lower end of the rod part  122  where the speaker  123  is installed, that is, at an upper end, and transfers acoustic energy supplied to the acoustic transmission portion  122   a  to the outside of the acoustic transmission portion  122   a . The opening/closing part  125  may be provided at one end of the rod part  122  in a slide structure, a hinge structure, or a dial structure, and is provided with a motor  125   a  so that opening and closing may be controlled by the controller  140 . The opening/closing part  125  may be controlled by the vehicle controller  230  installed in the vehicle  200  when mounted in the vehicle  200 . 
     The wheels  130  are installed on the main body  110  and the steering unit  120  and rotated by the power generated by the main body  110 . The wheels  130  may be installed one by one on the main body  110  and the steering unit  120  in order to reduce a weight of the personal mobility device. 
     The controller  140  controls the speaker  123  and may generate a virtual engine sound through the speaker  123  when the user moves using the personal mobility device. The virtual engine sound may be composed of a driving sound of a power device such as an engine driving sound and a motor driving sound and prevents collisions with pedestrians by recognizing the approach of the personal mobility device to the pedestrians. The controller  140  may independently control the speaker  123  and may control the speaker  123  in connection with the vehicle controller  230  provided in the vehicle  200  when mounted on the vehicle  200 . 
     Hereinafter, the acoustic transmission portion  122   a  provided in the rod part  122  will be described in detail. The acoustic transmission portion  122   a  is provided in the form of an empty space in the rod part  122 , and specifically, may be formed in the form of a hollow tube in the rod part  122 . The frequency characteristics of the acoustic transmission portion  122   a  may be changed according to a length L of the rod part  122  as shown in Equation 1 below, and it is preferable that the length L of the rod part  122  is 1 m or more in consideration of the user&#39;s body and low-pitched frequency characteristics. 
     
       
         
           
             
               
                 
                   
                     L 
                     = 
                     
                       
                         λ 
                         2 
                       
                       ⁢ 
                       n 
                     
                   
                   , 
                   
                     n 
                     = 
                     1 
                   
                   , 
                   2 
                   , 
                   3 
                   , 
                   … 
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     L: length of rod part 
     λ: Wavelength of frequency 
     n: The number of repetitions of wavelength 
     A resonant frequency of the acoustic transmission portion  122   a  may be expressed as Equation 2. The resonant frequency of the acoustic transmission portion  122   a  may appear as 171.5 Hz, 343 Hz, and 514.5 Hz when the length of the rod part  122  is 1 m, and when a resonant frequency of the speaker  123  is set to 100 Hz, the final frequency characteristic curve appears as shown in  FIG. 4 , indicating that a low frequency characteristic is satisfied. In  FIG. 4 , a horizontal axis represents frequency (unit: Hz), and a vertical axis represents sound pressure (unit: dB). 
     
       
         
           
             
               
                 
                   
                     
                       f 
                       n 
                     
                     = 
                     
                       
                         c 
                         
                           2 
                           ⁢ 
                           L 
                         
                       
                       ⁢ 
                       n 
                     
                   
                   , 
                   
                     n 
                     = 
                     1 
                   
                   , 
                   2 
                   , 
                   3 
                   , 
                   … 
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     2 
                   
                   ] 
                 
               
             
           
         
       
     
     fn: Resonant frequency 
     c: Constant 
     L: length of rod part 
     n: The number of repetitions of wavelength 
     That is, a vehicle speaker system using the personal mobility device according to an embodiment of the disclosure may satisfy a low frequency characteristic required by a subwoofer of the vehicle  200  when the length of the rod part  122  is 1 m or more and the resonant frequency of the speaker  123  is 100 Hz. 
     One or more frequency adjusters  122   b ,  122   c , and  122   d  protruding toward an inner center of the rod part  122  may be provided in the acoustic transmission portion  122   a . The frequency adjusters  122   b ,  122   c , and  122   d  may be provided in the form of a partition wall protruding toward the inner center of the rod part  122 , and may include the first frequency adjuster  122   b , the second frequency adjuster  122   c , and the third frequency adjuster  122   d.    
     The first frequency adjuster  122   b , the second frequency adjuster  122   c , and the third frequency adjuster  122   d  are formed along an inner circumferential surface of the rod part  122 , and a length between the first frequency adjuster  122   b  and the second frequency adjuster  122   c  and a length between the second frequency adjuster  122   c  and the third frequency adjuster  122   d  may be different from each other. 
     The resonant frequency of the acoustic transmission portion  122   a  may be adjusted by the frequency adjusters  122   b ,  122   c , and  122   d , and the resonant frequency of the acoustic transmission portion  122   a  adjusted by the frequency adjusters  122   b ,  122   c , and  122   d  may be expressed as Equation 3. 
     
       
         
           
             
               
                 
                   
                     
                       f 
                       
                         n 
                         , 
                         m 
                       
                     
                     = 
                     
                       
                         c 
                         
                           2 
                           ⁢ 
                           
                             L 
                             m 
                           
                         
                       
                       ⁢ 
                       n 
                     
                   
                   , 
                   
                     n 
                     = 
                     1 
                   
                   , 
                   2 
                   , 
                   3 
                   , 
                   … 
                   ⁢ 
                   
                       
                   
                   , 
                   
                     m 
                     = 
                     1 
                   
                   , 
                   2 
                   , 
                   3 
                   , 
                   … 
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     3 
                   
                   ] 
                 
               
             
           
         
       
     
     fn,m: Resonant frequency 
     c: Constant 
     Lm: Length of rod part or length of frequency adjuster 
     n: The number of repetitions of wavelength 
     In Equation 3, Lm refers to the length of the rod part  122  or lengths of frequency adjusters  122   b ,  122   c , and  122   d , and specifically, L1 refers to the length of the rod part  122 , L2 refers to a length between the speaker  123  and the first frequency adjuster  122   b , L3 refers to a length between the speaker  123  and the second frequency adjuster  122   c , and L4 refers to a length between the speaker  123  and the third frequency adjuster  122   d.    
     The final frequency characteristic curve appears as shown in  FIG. 6 , so that it may be seen that the resonant frequency controlled by the frequency adjusters  122   b ,  122   c , and  122   d  may secure an appropriate output for an audible sound wave. 
     That is, the resonant frequency of the acoustic transmission portion  122   a  may be adjusted by the frequency adjusters  122   b ,  122   c , and  122   d , and the final frequency characteristic curve may be adjusted by adjusting intervals between the frequency adjusters  122   b ,  122   c , and  122   d.    
     In  FIG. 6 , the horizontal axis represents frequency (unit: Hz), the vertical axis represents sound pressure (unit: dB), F_spkr refers to a resonant frequency of the speaker, F1,1 refers to a resonant frequency by L1, F1,2 refers to a resonant frequency by L2, F1,3 refers to a resonant frequency by L3, and F1,4 refers to a resonant frequency by L4. 
     The vehicle speaker system according to an embodiment of the disclosure may be provided by mounting the speaker system  100  of the personal mobility device on the vehicle  200 . 
     The speaker system  100  of the personal mobility device is mounted in the vehicle  200  to assist the speaker of the vehicle  200 , and the vehicle  200  is provided with an accommodating part  210 , a connection part  220  and the vehicle controller  230 . 
     The accommodating part  210  is provided in one space such as spaces in a trunk, a door and a side panel of the vehicle  200 , and the main body  110 , the steering unit  120 , the wheels  130  and the controller  140  are mounted therein. The accommodating part  210  may be provided in the form of an encloser to utilize acoustic energy transmitted through the speaker  123  as a low frequency. The encloser, which is a volume frame that maintains an outer skeletal frame of the speaker system, refers to a cabinet in which each of the speaker units is mounted and accommodated in the speaker system. 
     The accommodating part  210  may be provided in a form connected to a separate enclosure in order to utilize the speaker system  100  of the personal mobility device as a subwoofer by improving the low-pitched characteristic of a vehicle speaker system using the speaker system  100  of the personal mobility device. 
     The connection part  220  electrically connects the battery  111  and the speaker  123  to the vehicle  200  and transmits power and control signals to the battery  111  and the speaker  123 . The connection part  220  may transmit a control signal to the speaker  123  using a wireless communication module, and for example, may transmit a control signal to the speaker  123  using a Bluetooth module. 
     The vehicle controller  230  controls the speaker  123  through the connection part  220 , and may directly control the speaker  123  installed in the speaker system  100  of the personal mobility device according to a speaker output of the vehicle  200 , or may indirectly control the speaker  123  through the controller  140  installed in the speaker system  100  of the personal mobility device. 
     The vehicle controller  230  may open the opening/closing part  125  by controlling the motor  125   a  installed in the opening/closing part  125  and may transmit acoustic energy supplied to the acoustic transmission portion  122   a  to the accommodating part  210  by opening the opening/closing part  125 . 
     As is apparent from the above, a speaker system of a personal mobility device according to an embodiment of the disclosure generates a virtual engine sound through a speaker when driving, so that pedestrians can be informed of the approach of the personal mobility device and pedestrian accidents can be prevented in advance. 
     A vehicle speaker system using the speaker system of the personal mobility device according to an embodiment of the disclosure assists a speaker of a vehicle by using the personal mobility device, so that the vehicle speaker system can be implemented using a small space. 
     In addition, because the speaker system of the personal mobility device is used to assist the speaker of a vehicle, a broadband characteristic of a speaker can be secured with only one of the speaker. 
     Although the present disclosure has been described above with reference to exemplary embodiments of the present disclosure, those skilled in the art will understand that the present disclosure may be variously modified and changed without departing from the spirit and scope of the present disclosure set forth in the appended claims.