The present invention relates to a speaker system, and particularly to a speaker system in which a woofer and a group of tweeters are substantially coaxially arranged.
To improve sound quality, many speakers adopt a 2-way system in which sound waves in a low-pitched sound range are emitted from a woofer and sound waves in a high-pitched sound range are emitted from a tweeter. In a common 2-way speaker system, the tweeter and the woofer are arranged in a vertical direction or a horizontal direction. Therefore, the common 2-way speaker system needs to have a wider area on a front surface (baffle plate) thereof than a single-cone speaker having one cone.
Here, proposed is a speaker system in which the tweeter and the woofer are arranged in a front-back direction. In many of such speaker systems, the tweeter and the woofer are coaxially arranged, and such speaker system is called “coaxial speaker” (see Patent Document 1 for example). In a common coaxial speaker, the tweeter is smaller than the woofer, and is arranged in front of the woofer or inside a cone of the woofer. Therefore, the area of the front surface of the speaker system can be reduced, so that the speaker system can be reduced in size.
Patent Document 1: Japanese Laid-Open Patent Application Publication 2004-165917
As described above, the 2-way speaker system emits the sound waves in the low-pitched sound range from the woofer and emits the sound waves in the high-pitched sound range from the tweeter. However, there is a frequency range of sound waves which are emitted from both the woofer and the tweeter. To be specific, such frequency range is a frequency range including a crossover frequency and frequencies in the vicinity of the crossover frequency.
d) is a diagram showing that a range (range in which a sound of a certain sound pressure level can be heard) of a directivity angle of the woofer 22 and a range of a directivity angle of the tweeter 23 overlap each other. As shown in
Here, an object of the present invention is to provide a speaker system in which a woofer and a group of tweeters are coaxially arranged, and the sound waves emitted from the woofer and the sound waves emitted from the tweeter are less likely to interfere with each other in at least one direction, and whose sound pressure frequency characteristics easily stabilize in at least one direction.
To solve the above problems, a speaker system of the present invention includes: a woofer; and three or more tweeters, wherein the tweeters are arranged in front of the woofer in a circular-arc formation.
With this configuration, since the tweeters are arranged in a line, the group of three or more tweeters serves as one sound source by a line array effect, and can be regarded as one speaker having a large opening. In addition, the center position of the sound wave spreading in a circular-arc shape from the tweeters can be made closer to the center position of the sound wave spreading in a circular-arc shape from the woofer. Further, the directivity angle of the group of the tweeters becomes small by the line array effect. However, since the tweeters are arranged in a circular-arc formation, the directivity angle of the group of the tweeters can be made closer to the directivity angle of the woofer. Here, the line array effect means that by arranging a plurality of speakers in a line, sound sources from the speakers become a single sound source and a line sound source, and the sound wave is transmitted in a line. By using this effect, the speaker system can efficiently emit the sound whose energy is less likely to attenuate as compared to a single speaker that is a point sound source and emits the sound spreading in a spherical shape.
Moreover, in the speaker system, in a flat plane including axes of two tweeters arranged on both ends among the three or more tweeters, a directivity angle of the group of the three or more tweeters at a crossover frequency may be substantially the same as a directivity angle of the woofer at the crossover frequency. With this configuration, the directivity angle of the group of the tweeters and the directivity angle of the woofer are substantially the same as each other at the crossover frequency. Therefore, the directivity angle does not significantly change when the output of the speaker system changes from the woofer to the tweeters. On this account, the sound pressure frequency characteristics easily stabilize even in the vicinity of the crossover frequency.
Moreover, in the speaker system, the directivity angle of the group of the three or more tweeters at the crossover frequency may be 90% to 110% of the directivity angle of the woofer at the crossover frequency. If the directivity angle is within this range, the above effect at the crossover frequency can be adequately obtained.
Moreover, in the speaker system, an axis of the tweeter located on a more outer side among the three or more tweeters may incline more outwardly. With this configuration, the axis of the tweeter located on a more outer side inclines in a fan-like form as with the propagation of the sound wave. Therefore, the tweeters can emit the sound wave whose propagation is similar to the propagation of the sound wave of the woofer.
Moreover, in the speaker system, an angle between the axes of two tweeters located on both ends among the three or more tweeters may be 70% to 90% of the directivity angle of the woofer at the crossover frequency. Even if the angle between two tweeters arranged on both ends among three or more tweeters is adjusted to be the same as the directivity angle of the woofer at the crossover frequency, the directivity angles of the woofer and the group of the tweeters do not coincide with each other at the crossover frequency. In contrast, with the above configuration, the directivity angle of the group of three or more tweeters at the crossover frequency can be set to be substantially the same as the directivity angle of the woofer at the crossover frequency.
Moreover, the speaker system may further include a tweeter frame hanged between two opposed positions located in the vicinity of a peripheral edge of the woofer, wherein: the three or more tweeters may be attached to the tweeter frame; and the tweeter frame may have a flare-shape side wall to serve as a constant directivity horn. With this configuration, by the effect of the constant directivity horn, the directivity angle in a direction perpendicular to the direction in which the tweeters are arranged can be adjusted.
Moreover, the speaker system may further include a rear cover covering rear portions of the three or more tweeters, wherein in a state where the rear cover is attached to the tweeters, the rear cover may have a mountain-like shape whose sharp angle faces the woofer. With this configuration, it is possible to prevent the sound wave emitted from the woofer from reflecting on rear portions of the tweeters.
Moreover, the speaker system may further include an enclosure to which the woofer is attached, wherein: the enclosure may have an inclined surface on a rear side thereof; and in a case where the enclosure is placed on a horizontal surface by using the inclined surface as a bottom surface, the axis of the woofer may extend diagonally upwardly, and the three or more tweeters may be arranged in a horizontal direction. With this configuration, in a case where, for example, the speaker system is placed on a floor, and the range of emission of the sound wave in the horizontal direction may be narrow, the speaker system can efficiently emit the sound wave whose energy is less likely to attenuate in this range.
In accordance with the present invention, in a flat plane including axes of two tweeters arranged on both ends among three or more tweeter, a center position of a sound wave spreading in a circular-arc shape from the tweeters can be made closer to a center position of a sound wave spreading in a circular arc shape from the woofer. In addition, the directivity angle of the group of the tweeters can be made closer to the directivity angle of the woofer. With this, the present invention can provide a speaker system in which the woofer and the group of the tweeters are coaxially arranged, the sound waves emitted from the woofer and the sound waves emitted from the tweeter are less likely to interfere with each other in at least one direction, and whose sound pressure frequency characteristics easily stabilize.
Hereinafter, a best mode for carrying out a speaker system 1 of the present invention will be explained in reference to
The woofer 2 is a cone speaker, and serves to emit sound waves in a low-pitched sound range. As shown in
The tweeter 3 is a cone speaker, and serves to emit sound waves in a high-pitched sound range. As shown in
Referring again to
The directivity angle of the group of six tweeters 3 does not have to coincide with the directivity angle of the woofer 2 at the crossover frequency. To be specific, the above effects can be adequately obtained as long as the directivity angle of the group of six tweeters 3 is in a range from 90% to 110% of the directivity angle of the woofer 2 at the crossover frequency. Such setting of the directivity angle can be realized by setting the angle between the axes of two tweeters 3 arranged on both ends to be in a range from 70% to 90% of the directivity angle of the woofer 2 at the crossover frequency. In the present embodiment, the above setting is realized by setting the angle between the axes of two tweeters 3 arranged on both ends to be 40 degrees, i.e., 80% of 50 degrees which is the directivity angle of the woofer 2 at the crossover frequency.
The enclosure 4 serves to fix the tweeter frame 5 to which the woofer 2 and the tweeter 3 are mainly attached.
The tweeter frame 5 serves to fix the tweeters 3. As shown in
The tweeter frame 5 is mainly constituted by a base portion 7 and side walls 8. The tweeters 3 are attached to the base portion 7. The width of the base portion 7 is substantially the same as the diameter of the opening of the tweeter 3, but both end portions connected to the enclosure 4 are wider to increase the strength. Moreover, the base portion 7 has a circular-arc shape, and the center position of this circular arc is substantially the same as the center position of the sound wave spreading in the circular-arc shape from the woofer 2. Moreover, the axis of the tweeter 3 intersects with the base portion 7 at right angle. With this configuration, the tweeter 3 can emit the sound wave along the propagation of the sound wave emitted from the woofer 2.
The side wall 8 has a flare shape extending along a side end portion of the base portion 7 and spreading outwardly. With this, the tweeter frame 5 can serve as a constant directivity horn. Therefore, the directivity can be controlled in not only a direction in which the tweeters 3 are arranged but also a direction perpendicular to the direction in which the tweeters 3 are arranged. Thus, the sound wave can be efficiently emitted. Note that the base portion 7 and the side wall 8 are substantially the same in thickness as each other, and the thickness is about 7 mm.
The rear cover 6 is a member covering rear portions of the tweeters 3. Moreover, the rear cover 6 is attached to the tweeter frame 5 by screws so as to sandwich the tweeters 3.
The foregoing has explained the configuration of the speaker system 1 according to the present embodiment. In a case where the common 2-way speaker system (system in which the woofer and the tweeter are not coaxially arranged) emits sound for listeners near the system, the listeners often recognize that the positions of the sound sources, such as the tweeter and the woofer, are different from each other, and the sound is unnatural. In contrast, even in a case where 2-way and 3-way speaker systems using a coaxial system emit sound for listeners near the system, the above unnatural sound is not emitted. Further, the 2-way speaker system in which the woofer and the group of three or more tweeters are coaxially arranged as in the present invention has an advantage that the sound emitted for the listeners near the system is not unnatural, and in addition, it can emit the sound for only a specific listener by controlling the directivity. Therefore, the present invention can realize a speaker system especially suitable for the application shown in
From the foregoing explanation, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Therefore, the foregoing explanation should be interpreted only as an example, and is provided for the purpose of teaching the best mode for carrying out the present invention to one skilled in the art. The structures and/or functional details may be substantially modified within the spirit of the present invention.
The present invention can provide a speaker system in which the woofer and the group of the tweeters are coaxially arranged, and the sound waves emitted from the woofer and the sound waves emitted from the tweeter are less likely to interfere with each other in at least one direction, and whose sound pressure frequency characteristics easily stabilize in at least one direction. Therefore, the present invention is useful in the technical field of the speaker system, especially in the technical field of the speaker system in which the woofer and the group of the tweeters are coaxially arranged.
Number | Date | Country | Kind |
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2006-308086 | Nov 2006 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2007/071943 | 11/12/2007 | WO | 00 | 9/9/2009 |