JP3521488B2 - Speaker device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker device provided with an acoustic tube on the back of a loudspeaker. 2. Description of the Related Art Conventionally, as one of the techniques for expanding the low-frequency range reproduction of a speaker device, a speaker device in which an acoustic tube is connected to the back of a speaker has been used. A conventional loudspeaker device in which this type of acoustic tube is connected will be described below with reference to the drawings. FIG. 3 is a sectional view showing the structure of the above-mentioned conventional speaker device. In FIG.
Reference numerals 2a, 2b, 2c, 2d, and 2e denote partition plates provided on the front plate and the rear plate of the cabinet 1, reference numeral 3 denotes an opening provided below the front plate of the cabinet 1, and reference numeral 4 denotes an upper portion of the front plate. Speaker. [0005] The operation of the conventional loudspeaker device configured as described above will be described below. Cabinet 1
Partition plates 2a, 2b, 2c, 2d, 2e provided in
Is a sound tube, and the sound emitted from the back of the speaker 4 passes through the sound tube and is radiated from the opening 3 provided at the lower part of the front plate. The above acoustic tube resonates at a specific frequency determined by its total length, and the overall length of the acoustic tube is L, and the speed of sound in the air is C.
Then, the resonance frequency (f _n ) becomes f _n = C / 4L × (2
n + 1) where n = 0, 1, 2,... n, and n = 0
In this case, a 1/4 wavelength is superimposed in the acoustic tube to cause resonance, acoustically increased sound is radiated from the opening 3 of the acoustic tube, and a significant improvement in efficiency near the bass reproduction limit is achieved. . Further, at a frequency at which a half wavelength is applied to the sound tube, the sound radiated from the front surface of the speaker 4 and the sound radiated from the front surface of the sound tube have an opposite phase to the sound from the front surface. The sound from the back of the speaker 4 is added in the same phase due to a half-wave phase delay, and the sound pressure level increases. Further, when n = 2, 3/4 is set in the acoustic tube.
As in the case where the wavelength is increased and n = 0, the opening 3
A more acoustically enhanced sound is emitted. Therefore, a high-efficiency speaker device can be realized in a low-frequency range. However, in the above-described conventional configuration, the acoustic tube repeats resonance even at a frequency of n = 2 or more, and the mid-high sound on the back of the speaker 4 is radiated through the acoustic tube. Is done. As a matter of course, while the sound in front of the speaker 4 is synthesized to produce peaks and valleys in the sound pressure, as shown by a dotted line in the reproduced sound pressure frequency characteristic diagram of FIG. there were. In addition, there is a method generally called a 3D system in which such a bass-only speaker device is added as a two-channel stereo center channel for reproducing mid-high frequencies. As described above, the middle and high frequency range is also radiated as described above, and there is a problem that it interferes with a two-channel speaker that reproduces the middle and high frequency range, causing deterioration of sound quality or poor localization. For this reason, a method of removing the above-mentioned sound interference by adding a signal whose middle and high frequencies have been cut to a low-tone speaker device by adding a filter characteristic to the electric circuit has been adopted, and the electric circuit becomes complicated. The problem was also included. The present invention solves the above-mentioned problems, and provides a high-performance bass-only speaker device capable of acoustically cutting the mid-high range as a low-range speaker and eliminating the influence of the middle-high range speaker. It is intended to provide. [0012] In order to solve this problem, a speaker device according to the present invention is provided with an acoustic tube for guiding sound waves having openings at both ends, and a sound tube connected in the middle of the path of the acoustic tube. Loudspeaker and shielding plates respectively connected to the openings at both ends of the acoustic tube via vibrating supports. According to this structure, sound waves radiated from the front and rear directions of the speaker are radiated through the shielding plates connected to the opening portions at both ends of the acoustic tube through vibrating supports. Sound waves in a low-frequency range lower than the resonance frequency of the plate are radiated into the air when the air at the opening of the sound tube and the shielding plate vibrate in the same phase while maintaining the principle of bass expansion and reproduction by resonance of the sound tube itself. On the other hand, a sound wave having a frequency higher than the resonance frequency of the shield plate is hardly radiated into the air because the shield plate plays an essential role and blocks the sound wave, so that the middle and high range is cut off. As described above, it is possible to cut the middle and high frequency range unnecessary for the speaker device dedicated to the low frequency without using an electric filter. Hereinafter, a speaker device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the structure of a speaker device according to the embodiment. In FIG. 1, reference numeral 5 denotes an acoustic tube continuously extending to the front and back sides of a speaker 6; Are connected to the openings at both ends of the speaker 6 via a vibrating support 8. The sound tube 5 is connected to the front side and the back side of the speaker 6 as a whole. The shield plate 7 is connected to the portion. The operation of the loudspeaker device of the present invention configured as described above will be described below. The shielding plate 7 coupled to the openings at both ends of the acoustic tube 5 via vibrating supports 8 vibrates by sound waves emitted from the speaker 6 to emit sound waves into the air.
At this time, sound waves having a frequency lower than the resonance frequency of the vibration system constituted by the shield plate 7 and the support 8 are radiated almost without attenuation, but sound waves having a higher frequency than the resonance frequency are blocked by the shield plate 7. It is not radiated into the air and is greatly attenuated. As a result, the principle of bass expansion and reproduction using the resonance phenomenon of the acoustic tube 5 is utilized as it is, and a speaker device having a frequency characteristic in which the middle and high frequency ranges are attenuated, as shown by a solid line in FIG. As compared with a bass device for reproducing low-pitched sound, the mid- and high-pitched sound range is cut off, and an ideal characteristic that only the low-pitched sound range can be reproduced is obtained. In this embodiment, the cross-sectional area of the acoustic tube 5 is constant. However, the cross-sectional area may be partially changed in accordance with the required bass reproduction characteristics. The number is not limited to one, and a similar effect can be obtained by providing a plurality of the same. As described above, the loudspeaker device according to the present invention is provided with the continuously extended acoustic tubes on the front and back sides of the loudspeaker, and can vibrate the shielding plate on the front side of the loudspeaker. A structure in which the sound tube is connected to the opening of the sound tube at one end via the support, and a similar shielding plate is also connected to the opening of the other end of the sound tube. By realizing the reproduction sound pressure frequency characteristic of only low-frequency sound reproduction in which the sound pressure in the region is attenuated, a speaker device dedicated to low-frequency sound can be realized without using an electric filter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural sectional view of a speaker device according to an embodiment of the present invention. FIG. 2 is a characteristic diagram showing a comparison between reproduced sound pressure frequency characteristics of the speaker device and a conventional speaker device. FIG. 3 is a cross-sectional view of the structure of a conventional speaker device. [Description of References] 5 Acoustic tube 6 Speaker 7 Shielding plate 8 Vibrating support

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Claims (1)

(57) [Claim 1] An acoustic tube for guiding sound waves having openings at both ends, a speaker coupled in the middle of the path of the acoustic tube,
Resonant phenomena of the sound tube, consisting of shield plates connected to the openings at both ends of the sound tube via vibrating supports
The bass range is enlarged and reproduced, and the shield plates at both ends are opened.
A speaker device that attenuates and reproduces the middle and high frequency range by using.