Patent Publication Number: US-2016234590-A1

Title: Speaker system

Description:
This application is a Continuation-In-Part of PCT Application No. PCT/JP2014/003175, filed Jun. 13, 2014, and claims the benefit of JP Application No. 2013-217231, filed Oct. 18, 2013, the contents of which are incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a speaker system that outputs a sound. 
     BACKGROUND ART 
     In recent years, a speaker system has been developed in which a plurality of loudspeakers are coaxially provided so as to precisely reproduce a sound from a low-frequency range to a high-frequency range. For example, a speaker system including a first loudspeaker; a second loudspeaker that is provided in front of the first loudspeaker and outputs a sound in a frequency range higher than that of the first loudspeaker; and a panel provided on a front surface of the second loudspeaker is known (see Patent Literature 1). 
     CITATION LIST 
     Patent Literature [Patent Literature 1] Japanese Unexamined Patent Application Publication No. 2008-136165 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the speaker system disclosed in the above-mentioned Patent Literature 1, the panel is provided along the outer periphery of a diaphragm of the second loudspeaker and is located on the front side of the first loudspeaker. This causes a problem that the sound output from the first loudspeaker is blocked by the panel, which results in degrading the sound quality. The size of the panel can be reduced so as not to block the sound. However, this may result in the degradation of the design due to the panel. 
     The present invention has been made to solve the above-mentioned problem, and a principal object of the present invention is to provide a speaker system that achieves a high quality design while maintaining a high quality sound. 
     Solution to Problem 
     The present invention includes a first loudspeaker; a second loudspeaker that is provided in front of the first loudspeaker and outputs a sound in a frequency range different from that of the first loudspeaker; and a panel provided on a front surface of the second loudspeaker. The panel includes a peripheral portion provided along an outer periphery of a diaphragm of the second loudspeaker. The panel has a diameter that is 2.5 times or less the diameter of a voice coil included in the first speaker. A distance from a neck portion included in the first speaker to the panel is equal to an integral multiple of a wavelength or a half-wave length of a frequency band of sound output from the vicinity of the neck portion. In the peripheral portion, at least one through-hole penetrating the panel in a sound output direction of the first and second loudspeakers is formed at a position opposed to the neck portion along an outer peripheral direction. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to provide a speaker system that achieves a high quality design while maintaining a high quality sound. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing a schematic configuration of a speaker system according to an embodiment of the present invention; 
         FIG. 2  is a perspective view showing a schematic configuration of a panel according to an embodiment of the present invention; 
         FIG. 3  is a top view of the panel shown in  FIG. 2 ; 
         FIG. 4  is a view showing a neck portion where a diaphragm and a voice coil of a first loudspeaker are connected to each other; 
         FIG. 5  is a top view of a panel in which nine through-holes are provided at regular intervals in a peripheral portion; 
         FIG. 6  is a sectional view of the panel taken along a line A-A shown in  FIG. 5 ; 
         FIG. 7  is a partially enlarged sectional view of a portion “B” shown in  FIG. 6 ; 
         FIG. 8  is a graph showing frequency characteristics when each through-hole according to an embodiment of the present invention is formed in the panel; 
         FIG. 9  is a view showing a through-hole formed so as to flare outward in a sound output direction of the first and second loudspeakers; and 
         FIG. 10  is a diagram showing the height of the panel. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present invention will be described below with reference to the drawings.  FIG. 1  is a perspective view showing a schematic configuration of a speaker system according to an embodiment of the present invention. A speaker system  10  according to this embodiment includes: a first loudspeaker  1  that mainly outputs a sound in a low-frequency range; a second loudspeaker  2  that mainly outputs a sound from a mid-frequency range to a high-frequency range; a third loudspeaker  3  that mainly outputs a sound in an ultra-high-frequency range (for example, about 10 to 200 kHz) which is higher than the high-frequency range of the second loudspeaker  2 ; and a panel  4  that is provided on a front surface of the second loudspeaker  2 . 
     The first loudspeaker  1  is a so-called woofer (WF) which is a speaker unit composed of a diaphragm, a voice coil, and the like. The second loudspeaker  2  is a so-called tweeter (TW). Similarly to the first loudspeaker  1 , the second loudspeaker  2  is a speaker unit composed of a diaphragm, a voice coil, and the like. The second loudspeaker  2  is provided in front of the first loudspeaker  1  and at a position overlapping the projection plane of the diaphragm of the first loudspeaker  1 . The third loudspeaker  3  is a so-called supertweeter (S-TW). Similarly to the second loudspeaker  2 , the third loudspeaker  3  is a speaker unit composed of a diaphragm, a voice coil, and the like. The third loudspeaker  3  is provided in front of the first loudspeaker  1  and beside the second loudspeaker  2 . The speaker system  10  according to this embodiment includes the third loudspeaker  3 . However, the configuration of the speaker system  10  is not limited to this. For example, the speaker system  10  may not include the third loudspeaker  3 . The second loudspeaker  2  and the third loudspeaker  3  may be coaxially provided in front of the first loudspeaker. Further, the first to third loudspeakers  1 ,  2 , and  3  may be configured as another drive system, such as a piezo-electric element, instead of using the above-mentioned voice coil. 
       FIG. 2  is a perspective view showing a schematic configuration of the panel according to this embodiment.  FIG. 3  is a top view of the panel shown in  FIG. 2 . The panel  4  is a member that has, for example, a substantially annular shape, and is formed of a synthetic resin such as plastic. The panel  4  is provided along the outer periphery of the diaphragm of the second loudspeaker  2 . The panel  4  covers the outer periphery of the second loudspeaker  2  which is provided in the vicinity of the center of the first loudspeaker  1 . The beauty of the shape of the panel contributes to achieving a high quality design for the speaker system  10 . Specifically, the configuration in which the panel  4  covers the outer periphery of the second loudspeaker  2  has such an effect that the entire system including the first loudspeaker looks well-organized and the aperture of the second loudspeaker  2  looks larger than its actual size. 
     The panel  4  includes a peripheral portion  41  that is provided along the outer periphery of the diaphragm of the second loudspeaker  2 ; a first projecting portion  42  that projects outward from the peripheral portion  41  and is provided with the third loudspeaker  3 ; a second projecting portion  43  that projects outward from the peripheral portion  41  at a position opposed to the first projecting portion  42 ; and a transition portion  45  that extends across an annular opening  44 . 
     The panel  4  is provided with the transition portion  45  for the purpose of protecting the second loudspeaker  2 . However, for the purpose of improving the sound quality of the second loudspeaker  2 , the panel  4  may not be provided with the transition portion  45 . The first projecting portion  42  has an opening  421  with a substantially circular shape. The diaphragm of the third loudspeaker  3  is exposed from the opening  421 , which allows the third loudspeaker  3  to output a sound through the opening  421 . The opening  421  may be provided with a transition portion  422  extending across the opening, for the purpose of protecting the third loudspeaker  3 . 
     Heretofore, there has been a problem that when the panel is provided along the outer periphery of the diaphragm of the second loudspeaker, the sound output from the first loudspeaker is blocked by the panel, which results in the degradation of the sound quality. A portion (neck portion) where the diaphragm and the voice coil of the first loudspeaker are connected to each other serves as an innermost-peripheral-side sound output region of the first loudspeaker ( FIG. 4 ). Accordingly, the sound in the high-frequency range (high frequency) is output from the diaphragm in the vicinity of the neck portion, which has a significant effect especially on the sound quality of the first loudspeaker. In other words, it is important to radiate the sound, which is output from the vicinity of the neck portion, to a user, without blocking the sound. 
     However, when the panel is provided along the outer periphery of the diaphragm of the second loudspeaker, the panel is located in the vicinity of the front side of the neck portion of the first loudspeaker and is opposed to a portion in the vicinity of the neck portion of the first loudspeaker. Accordingly, there is a possibility that the panel may block the sound output from the vicinity of the neck portion. Meanwhile, the size of the panel can be reduced so as not to block the sound. However, this may result in the degradation of the design due to the panel. 
     On the other hand, in the speaker system  10  according to this embodiment, at least one through-hole  46 , which penetrates the panel in a sound output direction of the first and second loudspeakers  1  and  2 , is formed along the outer peripheral direction in the peripheral portion  41  of the panel  4 . Accordingly, the sound output from the vicinity of the neck portion of the first loudspeaker  1  passes through each through-hole  46 , without being blocked by the panel  4 , and is directly transmitted to the user. For this reason, the degradation of the sound quality can be effectively suppressed. Meanwhile, the degradation of the sound quality can be suppressed while maintaining the size of the panel  4 . Thus, the beauty of the shape of the panel  4  contributes to achieving a high quality design for the speaker system. That is, a high quality design can be achieved while maintaining a high quality sound. 
     Note that since the large size of the panel  4  can be maintained, a secondary effect that the speaker system  10  has a highly merchantable quality can be expected. Specifically, maintaining the large size of the panel  4  allows the user to believe that the second loudspeaker  2  is larger than its actual size. Thus, it is believed that a larger sound (high output) is output from the second loudspeaker  2 , which leads to an increase in the merchantable quality of the loudspeaker. 
     Further, in this embodiment, the panel  4  has a diameter that is 2.5 times or less the diameter of the voice coil included in the first speaker  1 . The distance (the height H of the panel  4 ) from a neck portion  11  included in the first speaker  1  to the panel  4  is equal to an integral multiple of a wavelength or a half-wave length of a frequency band of sound output from the vicinity of the neck portion  11  (see  FIG. 10 ). 
     The sound (high-frequency component) output from the vicinity of the neck portion  11  of the first speaker  1  is blocked by the panel  4 . Due to the resonance in the characteristic frequency obtained when the height of the panel  4  is equal to the distance, DIP is generated in the characteristic frequency. However, the above-described configuration and the formation of the through-hole  46  in the panel  4  make it possible to further improve clear sound characteristics in the characteristic frequency. 
     For example, in the case of a wavelength in a frequency band of 4000 to 8000 Hz of sound output from the vicinity of the neck portion  11  of the first speaker  1 , the height of the panel  4  is preferably 20 to 40 mm. Further, the height of the panel  4  is not limited to the integral multiple of the half-wave length of the frequency of sound output from the vicinity of the neck portion  11  of the first speaker  1 . Also when the height of the panel  4  is equal to an integral multiple of the wavelength of the frequency of the sound, the same advantages effects can be obtained. 
     The through-holes  46  are formed, for example, at four positions, respectively, which are symmetrical to each other, along the peripheral direction of the peripheral portion  41 . In the state where the panel  4  is provided along the outer periphery of the diaphragm of the second loudspeaker  2 , each through-hole  46  of the panel  4  is opposed to a portion in the vicinity of the neck portion of the second loudspeaker  2 . Accordingly, the sound in the high-frequency range output from the vicinity of the neck portion of the first loudspeaker  1  passes through each through hole  46 , without being blocked by the panel  4 , and is transmitted to the user. Note that the through-holes  46  shown in  FIGS. 2 and 3  are examples only and are not particularly limited. The number, position, and size of the through-holes  46 , which are formed in the peripheral portion  41 , can be arbitrarily set. 
       FIG. 5  is a top view of the panel in which nine through-holes are provided at regular intervals in the peripheral portion.  FIG. 6  is a sectional view of the panel taken along a line A-A shown in  FIG. 5 .  FIG. 7  is a partially enlarged sectional view of a portion “B” shown in  FIG. 6 . 
     As shown in  FIG. 7 , an isolation wall  461  extending in the sound output direction of the first and second loudspeakers  1  and  2  is formed outside the through-hole  46 . This isolation wall  461  isolates the sound output from the first and second loudspeakers  1  and  2 , thereby preventing the sound output from the first loudspeaker  1  from traveling to the second loudspeaker  2 . For example, when the sound output from the first loudspeaker  1  travels to the second loudspeaker  2  and the sounds output from the first and second loudspeakers  1  and  2 , respectively, have opposite phases, the sound output from the second loudspeaker  2  is reduced by the sound output from the first loudspeaker  1 , which may result in the degradation of the sound quality. In this embodiment, the provision of the isolation wall  461  can suppress the degradation of the sound quality. 
     A thickness W of the isolation wall  461  is set to, for example, about 2.0 to 2.5 mm. However, the thickness W is not limited to this. For example, the thickness W may be set to about 3.0 mm. The thickness W can be arbitrarily set as long as the sound output from the first speaker can be prevented from traveling to the second speaker as described above. 
     For example, as shown in  FIG. 3 , an angle X 1 (°) of each through-hole  46  is an angle formed between a center line passing through the transition portion  45  and a radial center line passing through each through-hole  46 . A lateral width X 2  (°) of each through-hole  46  is an angle formed between a radial center line passing through each through-hole  46  and a radial center line passing through an end of each through-hole  46 . A radial center X 3  (mm) of each through-hole  46  is a distance from the center of the annular panel to the radial center position of each through-hole  46 . A radial width X 4  (mm) of each through-hole  46  is the width of each through-hole in the radial direction. Note that in this embodiment, the through-holes  46  have the same shape, but the shape of each through-hole  46  is not particularly limited. The through-holes  46  may have different shapes. 
     In this embodiment, the lateral width X 2 , the radial center X 3 , and the radial width X 4  of each through-hole  46  of the panel  4  are appropriately set, thereby making it possible to control the frequency of the sound passing through each through-hole  46 . 
       FIG. 8  is a graph showing frequency characteristics when each through-hole according to this embodiment is formed in the panel. In  FIG. 8 , the longitudinal axis represents a sound pressure level. As shown in  FIG. 8 , the DIP value is minimized in the vicinity of 5 kHz and resonance is generated. Thus, it can be found that the effect of a high quality sound due to each through-hole  46  of the panel  4  is maximized in the vicinity of 5 kHz. 
     In the embodiment described above, the plurality of through-holes  46  penetrating the panel in the sound output direction of the first and second loudspeakers  1  and  2  are formed along the outer peripheral direction in the peripheral portion  41  of the panel  4 . With this configuration, a high quality design can be achieved while maintaining the high quality sound of the speaker system  10 . 
     The isolation wall  461  that extends in the sound output direction of the first and second loudspeakers  1  and  2  and isolates the sound output from the first loudspeaker  1  from the sound output from the second loudspeaker  2  is provided outside the through-holes  46 . With this configuration, the degradation of the sound quality caused when the sound output from the first loudspeaker  1  travels to the second loudspeaker  2  can be suppressed. 
     Note that the present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the scope of the invention. For example, in the above embodiment, the shape of the upper end of each through-hole  46  is the same as that of the lower end of each through-hole  46 , but the shapes of the upper and lower ends of each through-hole are not particularly limited. The upper end of each through-hole  46  may be formed with a radius greater than the radius of the lower end thereof. For example, as shown in  FIG. 9 , each through-hole  46  may be formed so as to flare outward in the sound output direction of the first and second loudspeakers  1  and  2 . With this configuration, the effect of high quality sound due to the through-holes  46  becomes more satisfactory. 
     This application is based upon and claims the benefit of priority from Japanese patent application No. 2013-217231, filed on Oct. 18, 2013, the disclosure of which is incorporated herein in its entirety by reference. 
     REFERENCE SIGNS LIST 
     
         
           1  FIRST LOUDSPEAKER 
           2  SECOND LOUDSPEAKER 
           3  THIRD LOUDSPEAKER 
           4  PANEL 
           10  SPEAKER SYSTEM 
           41  PERIPHERAL PORTION 
           42  FIRST PROJECTING PORTION 
           43  SECOND PROJECTING PORTION 
           44  OPENING 
           45  TRANSITION PORTION 
           46  THROUGH-HOLE