JPH04325338A - Acoustic reproducing device for vehicle - Google Patents

Abstract

PURPOSE:To provide an acoustic reproducing device which is fitted with a speaker in the headrest of the seat of a vehicle, resolves the problem that the reproduced sound pressure frequency characteristic can not be satisfied as the headrest becomes larger, and can obtain the flat and wide-band reproduced sound pressure frequency characteristic for the lateral width of the headrest with no speaker without nearly widening the width. CONSTITUTION:An acoustic pipe 3 is connected to the front section of the vibrating plate of a speaker unit 1, a horn wall is formed with a sound absorbing material 4 in the acoustic pipe 3, a speaker device having a rectangular structure with a very narrow lateral width on the opening section of the horn wall is buried in a headrest 6, the speaker device can be fitted without nearly widening the lateral width of the headrest 6, and the flat and wide-band reproduced sound pressure frequency characteristic can be provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a headrest speaker device, which is a sound reproducing device for automobiles, and mainly includes a speaker installed in the headrest of a seat.

0002

2. Description of the Related Art The interior of an automobile has a large amount of noise due to road noise and engine noise during driving, and since the interior of the vehicle is a very narrow closed space, there are many standing waves. As a result, the sound field for reproducing sound is in a near worst state, and it is difficult to obtain a satisfactory sound even if all possible means are used, such as speaker characteristics, amplifier amplitude correction, time correction, etc. Ta.

[0003] Furthermore, since convertible cars are affected by the wind while driving, it has not been possible to enjoy music using the usual speaker layout in which speakers are mounted under the instrument panel or on the door of the car.

[0004] To solve this problem, a device called a "headrest speaker" or "pyro speaker" was developed. A sound reproduction device called a "pyro speaker" has been in practical use for some time.

A typical conventional sound reproduction device called a headrest speaker will be explained below with reference to the drawings.

FIG. 3 is a plan sectional view showing the structure of a conventional sound reproducing device. In FIG. 3, 1 is a speaker unit, 2 is a back cavity, 6 is a headrest, 7 is a cushioning material inside the headrest 6, and 8 is a Each represents a human head.

As shown in FIG. 3, this sound reproduction device has a speaker unit 1 placed near the outside of the human head (ear) 8, and emits sound from there, and is not affected by the interior space of the vehicle. Therefore, it was possible to provide high quality sound.

[0008]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional configuration, the diameter of the speaker unit 1 mounted in the headrest 6 was a very large problem.

That is, in order to reproduce mid-to-low frequencies with the aim of Hi-Fi, the diameter of the speaker unit 1 needs to be a certain size, and for this reason, the headrest 6
It had become impractical for use in automobiles because it expanded too much laterally and obstructed rear visibility.

Further, the output of the amplifier that drives the speaker unit 1 is usually as large as about 15 to 25 W, and small speakers for headphones or the like cannot be used due to the problem of input resistance.

[0011] For this reason, the speaker unit 1 that has been put into practical use has a round shape with a diameter of 6 cm to 8 cm or an oval shape of about 5 cm x 7 cm, and is constructed at the expense of sound quality and performance. There were only so many things.

[0012] Even when the speaker unit 1 of the above diameter is adopted, its width is 14 cm compared to a normal headrest (without the speaker unit 1 installed).
The vehicle became wider by approximately 18 cm, and issues remained in terms of design and rear visibility.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and provide a sound reproduction device for an automobile that can reproduce sound with excellent sound quality and performance without substantially increasing the width of the headrest. .

[0014]

[Means for Solving the Problem] In order to solve this problem, the automobile sound reproducing device of the present invention connects an acoustic tube that guides sound waves to the outside to the front of a speaker installed inside the headrest, and A horn wall is constructed by bonding a sound absorbing material formed with an inclination such that the area is small at the front part of the diaphragm of the speaker and large at the opening part, and the area is large at the opening part. By forming the headrest into a narrow slit or rectangular shape, the headrest has a narrow width structure.

[0015]

[Function] With this configuration, the sound waves generated by the diaphragm of the speaker unit are guided to the opening by the horn wall and acoustic tube, and due to the effect of the sound absorbing material forming the horn wall, the sound waves guided to the opening are guided to the opening. It is possible to absorb standing waves due to reflected waves that occur due to large changes in acoustic impedance at a certain point, and to obtain flat sound pressure frequency characteristics.

Furthermore, by making the opening of the horn wall rectangular, a speaker device with a very narrow structure in the horizontal direction can be realized, and by mounting this on the headrest,
Without increasing the width of a conventional headrest,
It is possible to realize an automotive sound reproducing device with flat characteristics over a wide band.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view, a plan sectional view, and a side sectional view showing the structure of an automobile sound reproducing device according to an embodiment of the present invention. In FIG. 1, 1 is a speaker unit; 2 is a speaker unit;
3 is a back cavity; 3 is an acoustic tube for guiding sound waves generated on the front surface of the diaphragm of the speaker unit 1; 4 is a sound absorbing material arranged and coupled inside the acoustic tube 3 and having a sound path section 5 in the center; 5; is a sound path provided in the sound absorbing material 4, 6 is a headrest, and 7 is a cushioning material in the headrest. The acoustic tube 3 has a rectangular opening, and the width of the opening is made as narrow as possible to suppress the overall width of the headrest 6.

Further, the sound absorbing material 4 is formed to have a slope such that the area is small at the front surface of the diaphragm of the speaker unit 1, and the area is large at the opening, thereby forming a horn wall.

[0020] The operation of the thus constructed automobile sound reproducing apparatus will be described below.

Sound from the back of the diaphragm of the speaker unit 1 is confined within the cavity 2, but sound waves emitted from the front of the diaphragm are guided to the opening via the sound path section 5 and radiated. However, due to the sudden change in acoustic impedance that occurs at the opening, a portion of the sound waves that have been guided to the opening become reflected waves and tend to return to the diaphragm surface. This reflected wave is absorbed by the sound absorbing material 4 placed inside the acoustic tube 3, thereby making it possible to prevent standing waves generated inside the acoustic tube 3.

Generally, in a speaker device connected to a horn or sound tube, a reflected wave is generated due to a sudden change in impedance that occurs at the opening, and this reflected wave is almost determined by the length of the horn or sound tube 3. Since resonance occurs at the frequency of the sound and a standing wave is generated, the reproduced sound pressure frequency characteristic becomes a characteristic with large peaks and dips.

Note that the resonance caused by this reflected wave has no effect and a flat characteristic can be obtained if the length of the horn or acoustic tube 3 is sufficiently longer than the wavelength of the frequency band to be reproduced. It has been considered difficult to put into practical use a horn or acoustic tube 3 having a sufficient length when the speaker unit 1 is mounted inside the speaker unit 6. However, the automotive sound reproducing device according to the present invention solves these problems as described above, and can easily obtain high input resistance and flat reproduced sound pressure frequency characteristics despite its small size.

FIG. 2 shows the reproduced sound pressure frequency characteristics of the automobile sound reproduction device according to the present invention, and for comparison, the same characteristics of a speaker device with a horn or acoustic tube, and a conventional headrest speaker are also shown for reference. ing. The sound reproduction device for an automobile according to the present invention has a characteristic A shown by a solid line, and a flat reproduced sound pressure frequency characteristic is obtained from the low range to the high range. In addition, a speaker device with a horn or acoustic tube has characteristic B shown by the dotted line, and as mentioned above, a standing wave is generated by the reflected wave generated in the acoustic tube, and the reproduced sound pressure frequency characteristic has large peaks and dips. becomes.

[0025] Furthermore, the conventional headrest speaker has characteristic C shown by the dashed line, resulting in insufficient sound in both the bass and treble ranges.

The reproduction sound pressure frequency characteristics were measured by placing a dummy head (artificial head) at the position of a human head in front of the headrest 6. The automotive sound reproduction device according to the present invention has a configuration in which the width of the opening is very narrow, so it is possible to obtain good directional characteristics, and as a result, the high-frequency characteristics deteriorate even depending on the position (angle) of the ear. There is no. Furthermore, in the present invention, since the volume of the sound path section 5 also becomes the mass when viewed from the speaker unit 1, the mass of the vibration system of the speaker unit 1 increases, and the reproduced sound pressure frequency characteristics in the bass range are also broadened.
It can reproduce a wide range of sounds, from bass to treble, in a flat manner.

[0027]

As described above, the automobile sound reproducing device according to the present invention has a speaker device in which a horn wall is formed by bonding a sound absorbing material to the inside of a sound pipe, and is installed in the headrest. This eliminates the disadvantages of insufficient bass and treble ranges in the reproduced sound pressure frequency characteristics and the widening of the headrest, which was seen in the "Speaker" or "Pyro Speaker", and the width of the headrest does not expand much compared to the width of the headrest when there is no speaker. It is possible to realize a sound reproducing device for an automobile that has a flat reproduced sound pressure frequency characteristic and can reproduce a wide band.

[Brief explanation of drawings]

[Fig. 1] (a), (b), (c) A front view, a plan sectional view, and a side sectional view taken along line X-X' showing the configuration of an automobile sound reproducing device according to an embodiment of the present invention.

[Figure 2] Reproduction sound pressure frequency characteristic diagram according to the same example

[Figure 3]
Cross-sectional plan view of a conventional “headrest speaker”

[Explanation of symbols]

1 Speaker unit 2 Back cavity 3 Sound tube 4 Sound absorbing material 5　Ondo Club 6 Headrest 7 Cushioning material 8 Human head

Claims (2)

[Claims] Claim 1: An acoustic tube that guides sound waves to the outside is connected to the front of a speaker installed inside the headrest of a car seat,
An automotive acoustic system in which a horn wall is formed by supplying a sound absorbing material with an inclination such that the area is small at the front part of the diaphragm of the speaker and large at the opening part inside the acoustic tube. playback device. 2. The automobile sound reproducing device according to claim 1, wherein the opening of the horn wall has a vertically elongated rectangular shape.