JPH04223697A - On-vehicle speaker device - Google Patents

Abstract

PURPOSE:To obtain a high efficient and flat frequency characteristic over a wide frequency band by raising the matching of acoustic impedance of an acoustic tube and vehicle interior space. CONSTITUTION:A speaker for low-pitched sound 23 is provided under the rear seat of a vehicle room 21, partitions 26 are provided at front and rear two spots in the internal cavity of a columnar body frame 25 which is in the bottom part of a body, the one end of an acoustic tube 24 formed between the front and rear partitions 26 is connected to the speaker for low-pitched sound and the other end of the acoustic sound 24 is made opened downward a dashboard 29.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker device for use in a vehicle.

0002

2. Description of the Related Art A conventional vehicle-mounted speaker device configured as shown in FIG. 6 is known, for example.
To explain based on the drawings below, 1 is a vehicle interior, and 2 is a trunk room. This trunk room 2 houses a bass speaker 3 having a large-area diaphragm and is equipped with a bass reflex port 4 for reproducing deep bass sounds. A large capacity speaker cabinet 5 is provided. Also, dashboard 6
A speaker 7 for medium and high frequencies is installed inside.

0003

Problems to be Solved by the Invention Generally, in order to reproduce deep bass sounds, a large volume is required for the speaker device. However, the space that can secure a large volume inside the vehicle is limited to the trunk room, door compartment, etc. In the conventional configuration shown in FIG. 6, since the speaker cabinet 5 is installed in the trunk room 2, the storage space for luggage and the like in the trunk room 2 is reduced accordingly. Furthermore, even if a speaker device is installed in the door pocket, the comfort of the vehicle interior must be sacrificed.

[0004] Furthermore, when a speaker device is attached to a trunk room, a door compartment, etc., when reproducing bass sounds in a vehicle interior, the strength is insufficient. Therefore, energy loss due to unnecessary vibration of the mounting portion is also large, causing chatter and muffled sounds.

Furthermore, in the sound field in the vehicle interior created by the conventional configuration shown in FIG. Since the speaker 3 is installed in the trunk room 2, it is localized behind the listener, and the sound field lacks a sense of unity between the bass range and the middle and high ranges.

[0006] Also, the acoustic power radiated from the speaker device into the sound field space is determined by the radiation impedance on the driving surface of the sound field space. However, in the conventional speaker device shown in FIG. 6, the acoustic impedance matching between the speaker device and the vehicle interior space is not considered at all, so it is difficult to optimize the acoustic power radiation efficiency and frequency characteristics in the vehicle interior space. I can't.

The present invention solves the above-mentioned problems by installing a speaker device without using the space in the vehicle interior or trunk room for the speaker device, and by providing a low-frequency range that is integrated with the mid-high range. The purpose is to create a sound field within the vehicle interior, improve the acoustic impedance matching between the speaker system and the interior space of the vehicle, and obtain highly efficient and flat frequency characteristics over a wide frequency band. It is.

[0008]

[Means for Solving the Problems] In order to solve this problem, the present invention provides a vehicle-mounted speaker device equipped with an acoustic tube and a driver, which provides a vehicle interior space as seen from a sound radiation surface of the speaker device. Among the frequencies at which the imaginary part of the acoustic impedance of The shape of the acoustic tube and the constants of the driver are set as follows.
In addition, the opening of the acoustic tube is provided at a position where the acoustic impedance matching between the acoustic tube of the speaker device and the interior space of the vehicle is maximized.

[0009]

[Operation] With the above-described configuration, the present invention allows a speaker device to be installed without using the space in the vehicle interior or trunk room for the speaker device, and creates a low-frequency sound field that is integrated with the mid-to-high frequency range in the vehicle interior. realizable. Furthermore, since the acoustic impedance matching between the speaker device and the interior space of the vehicle improves, highly efficient and flat frequency characteristics can be obtained over a wide frequency band.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. In general, the value of FS (the lowest frequency among the frequencies at which the imaginary part of the acoustic impedance to the vehicle interior space seen from the acoustic radiation surface of the speaker device is zero) is determined by the volume, shape, etc. of the vehicle interior space, or the speaker device. It is determined by the size of the acoustic radiation surface. However, the value of FS in the actual vehicle interior space is approximately 10H.
z ~ 40Hz, so reproduction of frequency bands below this range can be achieved by equalizing the speaker device's FO (low-frequency reproduction limit frequency in free space of a single speaker device) and FS. However, the design of the playback sound field for higher frequency bands requires control using other methods.

The acoustic power radiated from the sound tube of the speaker device into the sound field is determined by the radiation impedance at the opening of the sound tube, which is the connection point between the sound tube and the sound field. Therefore, the opening of the acoustic tube is provided at a position where the acoustic impedance of the acoustic tube and the interior space of the vehicle best match. In other words, within the interior space of the vehicle,
The opening of the sound tube is provided in a horn-shaped location whose spatial shape maintains continuity to some extent with the shape of the sound tube.

FIGS. 3 and 4 show the relationship between two different shaped spaces whose volumes correspond to the interior space of a vehicle and the speaker device, where 11 is a bass speaker which is a driver;
2 is an acoustic tube, 13 is a horn-shaped space in which the spatial shape near the opening 14 of the acoustic tube 12 maintains continuity to some extent with the shape of the acoustic tube 12, and 15 is a simple cubic space. FIG. 5 shows the results of calculating frequency characteristics in the reproduced sound fields in these two types of spaces 13 and 15 using the finite element method.

In the reproduction sound field in the space 13, the acoustic tube 12
Since the acoustic impedance matching at the opening 14 of the acoustic tube 12, which is the connection point between the acoustic tube 12 and the sound field space, is better than that of the acoustic space 15, the radiation efficiency of the acoustic power from the acoustic tube 12 to the reproduction space increases as shown in FIG. It's also expensive. In addition, since the energy reflected to the acoustic tube 12 at the opening 14 of the acoustic tube 12 is small, intense resonance within the acoustic tube that would greatly impair the flatness of the frequency characteristics in the reproduced sound field is also suppressed. High efficiency and flat frequency characteristics can be achieved.

FIGS. 1 and 2 show an in-vehicle speaker device according to an embodiment of the present invention, in which reference numeral 21 indicates a vehicle interior, and 22
is a trunk room, and since the bottom of the vehicle body is concave under the rear seat of the vehicle interior 21, a bass speaker 23, which is a driver, is provided here. Reference numeral 24 designates an acoustic tube formed between the front and rear partitions 26, which are provided in the internal cavity of a columnar body frame 25 at the bottom of the vehicle body. A throat portion 27 connected to the bass speaker 23 is provided at one end of the acoustic tube 24, and is configured to guide the acoustic output of the bass speaker 23 to the acoustic tube 24. 28 is an opening provided at the other end of the acoustic tube 24 so as to open under the dashboard 29. Reference numeral 30 indicates a speaker for medium and high frequencies provided within the dashboard 29.

As described above, if the opening 28 of the acoustic tube 24 is provided in the space under the dashboard 29, this space will be acoustically connected to the dashboard and floor on the top and bottom, and to the side walls on the left and right. Since it is an enclosed horn-shaped space, the acoustic impedance can be matched with the space inside the vehicle interior 21 at the opening 28 of the acoustic tube 24, so that the space inside the vehicle interior 21 can be efficiently and with flat frequency characteristics. Can radiate acoustic power.

Furthermore, the speaker device has low frequency reproduction limit frequencies FO and FS in the free space of the speaker device alone.
It is necessary to set the shape of the acoustic tube 24 and the constants of the driver so that the values are approximately equal. For this purpose, the position of the partition 26 inside the vehicle body frame 25 may be adjusted. For example, in this embodiment, if the value of FS determined by the volume, shape, etc. of the interior space of the vehicle compartment 21 is 38 Hz, the entire length of the sound tube 24 from the throat portion 27 at one end to the opening 28 at the other end corresponds to the frequency of FS. The position of the partition 26 may be adjusted so that the distance is 2.26 m, which corresponds to 1/4 wavelength.

Furthermore, by providing the bass speaker 23 outside the vehicle interior 21, a large volume for bass reproduction can be secured without using the space inside the vehicle interior 21 and the trunk room 22. Furthermore, since the speaker device is built into the vehicle body, there is no unnecessary vibration of the mounting part, and it is possible to reproduce low-pitched sounds with good sound quality.

Furthermore, since the opening 28 of the sound tube 24 is located in front of the listener, the speaker 30 for medium and high frequencies installed inside the dashboard 29 integrates with the medium and high range such as vocals that are localized in front. A sound field in the bass range can be achieved.

In this embodiment, as shown in FIG. 2, a similar speaker device is constructed of two speakers, one for the L channel and one for the R channel, for stereo reproduction.

Furthermore, as a modification of this embodiment, the acoustic tube 2
The position where the opening 28 of No. 4 is provided can be set at the end of the space surrounded by the top of the dashboard 29 and under the windshield in the passenger compartment 21, or the space surrounded by the top of the rear parcel and under the rear window. , each having a horn shape, the acoustic impedance matching between the acoustic tube 24 and the interior space of the vehicle interior 21 is good, and the same effects as in the above embodiment can be obtained.

[0021]

As described above, according to the present invention, a speaker device can be installed without using space in the vehicle interior or the trunk room for the speaker device, and a low-frequency sound field integrated with the mid-to-high frequency range can be achieved. can be realized inside the vehicle. Furthermore, since the acoustic impedance matching between the speaker device and the interior space of the vehicle improves, highly efficient and flat frequency characteristics can be obtained over a wide frequency band.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a vehicle-mounted speaker device according to an embodiment of the present invention.

FIG. 2 is a bottom view of a vehicle-mounted speaker device according to an embodiment of the present invention.

FIG. 3 is a schematic side view showing a speaker device according to an embodiment of the present invention connected to a horn-shaped space.

FIG. 4 is a schematic side view showing a speaker device according to an embodiment of the present invention connected to a cubic space.

5 is a graph showing calculation results of frequency characteristics of sound pressure in the two types of reproduction spaces shown in FIGS. 3 and 4. FIG.

FIG. 6 is a side sectional view of a conventional vehicle-mounted speaker device.

[Explanation of symbols]

11 Bass speaker 12 Sound tube 13 Space 14 Opening 15 Space 21 Cabin 22 Trunk room 23. Bass speaker 24 Acoustic tube 25 Body frame 26 Partition 27 Throat part 28 Opening 29 Dashboard

Claims (1)

[Claims] Claims: 1. A vehicle-mounted speaker device comprising a sound tube and a driver, wherein the speaker device has a sound tube and a driver, the speaker device having the highest frequency among the frequencies at which the imaginary part of the acoustic impedance to the vehicle interior space seen from the sound radiation surface of the speaker device is zero. Let FS be the low frequency and FO be the low frequency reproduction limit frequency in the free space of a single speaker device, then the shape of the acoustic tube and the constants of the driver are set so that FO and FS are approximately equal, and A vehicle-mounted speaker device, characterized in that an opening of the sound tube is provided at a position where the acoustic impedance matching between the sound tube of the speaker device and a vehicle interior space is maximized.