JPS58210800A - Acoustic device for vehicle - Google Patents

Abstract

PURPOSE:To perform reproduction at a necessary sound pressure level in a desired low frequency range to about 50Hz by making a hole with necessary area in a panel member, and supporting a diaphragm member at both opposite edges of the hole and confronting it to the hole. CONSTITUTION:The rectangular hole 8a with necessary area is formed in the panel member 8 at a driver arrangement position. The diaphragm member 9 made of a different material from the panel member 8 is supported fixedly at both lengthwise opposite edges of the hole 8a to face the opening part 8, and an exciting driver D is fitted nearly in the center of this diaphragm member 9. Namely, the driver D is supported in a beam shape on the panel member 8 by the rectangular diaphragm member 9. Concentrated mass added beam oscillation of two degree-of-freedom systems occurs to the diaphragm member 9, which generates sound pressure for low-frequency reproduction. In this case, the material, shape, size, etc., of the diaphragm member 9 are so selected that the lowest resonance frequency f0 (about 50Hz) is a desired frequency, so a sufficient output sound pressure level is obtained close to a desired low-frequency part of about 50Hz to improve the efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle acoustic device that uses a panel member such as a vehicle interior member as an acoustic vibration frequency.

Traditional vehicle kawaneq! For example, the I device is shown in Figures 1 to 3.
There is something like the one shown in the figure (%Ken-Sho 54-135114
Figure 1 shows the excitation driver 〇, which has an excitation plate (2) and a Kabani plate (
3) is fixed to form a case body, and a yoke (5) equipped with an annular magnet (4) in the center of the case body.
is installed. The yoke (5) is the pole piece (5a
) e and yoke plate) (5b) and shi are integrated with the magnet (4) to form a magnetic circuit having an air gap. +1) K elastically supported. Further, a coil (73) wound around a bobbin is arranged in the above-mentioned gap, and a warping pin is fixed to the vibration plate (2+).The driver D configured in this way is shown in FIGS. As shown in the figure, the panel speaker (8) that forms the rear compartment of an automobile is attached to the back side of the panel member (8) at the frame +l) using screws or the like. The driver D is directly attached to a panel member (8) for the interior of a vehicle, and the entire panel member (8) is used as an acoustic diaphragm. In addition to the interior parts of the vehicle interior, wall panels in the passenger compartment are also used, and such panel members (8) are made of materials such as compressed cardboard or plywood, and are generally rigid to the vehicle body, etc. at their outer edges. is fixed.

When the audio signal is energized to the coil (7), the magnet (4) side and the frame m side, that is, the excitation plate (2) side, vibrate relative to each other via the damper (6). The vibrations of the vibration plate (2) and the like are transmitted to the panel member (8), thereby preventing reproduction of bass frequencies.

Incidentally, this vehicle audio system is a suitable speaker because it can lower the lowest resonance frequency and reproduce even lower bass frequencies than other speakers such as cone speakers.

However, in the conventional vehicle acoustic device as described above, the entire panel member (8) is used as an acoustic diaphragm as it is, so plate vibration is generated using the solid leg portions on the outer periphery of the panel member (8) as nodes. As a result, the lowest natural resonance point cannot be kept low enough, and as shown in the reproduced frequency characteristics in Figure 4, the lowest resonance frequency f of the speaker is about several hundred Hz.Therefore, this type of vehicle acoustic To avoid the appearance of a peak in the desired bass reproduction range B that takes advantage of the characteristics of the device and lack flatness of the characteristics, and to output with a sufficient sound pressure level up to the desired bass range up to, for example, 50 Hz & degrees. The problem was that it was not possible. Further, there is a problem in that split vibration occurs in which each part of the panel member (8) vibrates in a different phase, resulting in a low output sound pressure level as a whole, a decrease in multi-efficiency, and poor transient response characteristics.

This invention was made by focusing on such conventional problems, and it is possible to form an opening with a required area in a panel member.1.
The above-mentioned problem can be solved by supporting a separate diaphragm member at both opposing edges of the hole so as to face the hole, and by attaching a driver for excitation to the diaphragm member. The purpose is

The present invention will be explained below based on the drawings. FIG. 5 and FIG. 6 are diagrams showing an embodiment of the present invention. Furthermore, the fifth
In the figures that follow, the same or equivalent members or parts as shown in FIGS. 1 to 3 are designated by the same reference numerals and redundant explanations will be omitted.

First, the configuration will be described. In this invention, a rectangular (rectangular) opening (8a) having a required area is bored in the driver mounting portion of the panel member (8)K. The opening area of the aperture (8a) is selected to be about 130 x 400 layers. A diaphragm member (9) made of a material different from that of the panel member (8) is fixedly supported by both longitudinally opposing portions of the aperture (8a) and faces the aperture (8a), A vibration excitation driver 〇 is attached to approximately the center of this diaphragm member (9). That is, the driver D is supported by a rectangular diaphragm member (9) in the form of a beam on the main body of the panel member (8). The diaphragm member' (9) is made of a material that functions appropriately as an acoustic diaphragm, such as foamed urethane, and has a thickness of approximately several mm and a planar area of the opening (
A very narrow slit α corresponding to the clearance for vibration is formed between the vibrating side line portions and the opening (8a).

Next, the effect will be explained. When the audio bond is energized to the coil (71, dry <-I) inside the magnet (4)
The side and the excitation plate (2) side vibrate relative to each other via the damper (6), and this vibration excites the diaphragm member (9). Then, 2-confessional mass-added beam vibration occurs in the diaphragm member (9), generating sound pressure and reproducing a low frequency range. At this time, the material, shape, etc. of the diaphragm member (9) have the lowest resonant frequency f. Therefore, the lowest resonant frequency f is selected as the desired frequency, as explained by the following equation. is, for example, about 50H2, and the reproduction frequency characteristic shifts as shown by the solid line in FIG. Therefore, the flatness of the characteristics increases within the desired bass reproduction range B that takes advantage of the characteristics of this type of vehicle audio device, and a sufficient output sound pressure level can be obtained up to the desired low frequency range of 50Hz 8 degrees. Then the lowest resonant frequency f. The lowering effect of is explained in more detail using an equation.

Now ml; Vibration system mass including the diaphragm member (9), kl;
Spring constant of this vibration system, ml; Magnet system mass, kl
; Assuming that the spring constant of the driver (tambar) is ω = 2πf, and an excitation force of 1'cosωt is applied to the fan ωt1 vibration system mass m2 and the mag9 system mass m2,
When examining the motion for the mass of the vibrating system, the slow effect equation is m1d2
x1/dt2+Jx++1cz(x+x2)--F
ccsωt −■rr+2d2x2/ d t2
+ kl(X2 XI) = Fcosωt
...(L)'. Still forced vibration xl = a1cosωt, X2 = a2casω
Assuming that t (at s a2: amplitude)...■,
Substituting this into formulas ■ and ■', al (and a2) is obtained and al=Fm2ω2/((m2cc+2+kx+2)(
-+n2ω2+ becomes 2) k22J...■. Here, the lowest resonant frequency f. is the frequency when the amplitude al becomes infinite (assuming there is no mechanical resistance), so
Set the denominator of the above formula ■ to zero as follows, (-mtω”
+ to 1+ to +) (m2cc+2+ to 2) -kz2=+3
...■ Find ω (=2πf) k that satisfies this formula 0, and settle for the higher value of the two solutions. In this way, find...■ Still the spring constant k I Fd of the vibration system, L: Beam (
The length of the diaphragm member), E: Young's modulus, I: section modulus of the beam, is expressed by the following formula 0.

k1=t, 3/ (192EI)
...■ From both formulas (■) and (■) above, the spring constant of the vibration system is determined by the external dimensions of the beam, that is, the diaphragm member (9), and the lowest resonant frequency f. Dove spring constant k1%
The minimum resonant frequency f0 can be set to a desired value by selecting the material of the diaphragm member (9) and its external dimensions as described above. It is possible to specify the following.

Next, FIGS. 8 and 9 show other embodiments of the present invention. In this embodiment, an acoustic shield (12a) is attached to both sides of the panel member (8) along the street (11).
(12b). Acoustic shield (
The planting height h of 12a) and (12b) is also slightly higher than the maximum amplitude of the diaphragm member-9).

To explain the operation, as shown in FIG. 9, the diaphragm member (9) is excited and vibrates, and the opening area of the diaphragm is expanded. At this time, there is a tendency for vibrating air to enter and exit both the front and back sides of the diaphragm member (9) through this enlarged slit αυ, but the acoustic shields (12a) and (12b) substantially restrict the area expansion of the slit aυ, allowing the vibrating air to flow in and out. Control the tendency of people to come in and go out. Therefore, a decrease in the output sound pressure level due to cancellation of low-frequency out-of-phase sound waves caused by the inflow and outflow of vibrating air is prevented, and efficiency is improved. 1st
The characteristic shown by the solid line in the reproduced frequency characteristic of Fig. 0 shows the improvement in the sound pressure level in the low frequency range due to the above-mentioned effect.

As detailed above, according to the present invention, an aperture having a required area is formed in the panel member, and a separate diaphragm member is supported by both opposing edges of the aperture and faces the aperture. ,
The desired material and shape of the diaphragm can be selected arbitrarily, and it is possible to reproduce the desired low frequency range of about 5QHz at the desired sound pressure level, making full use of the characteristics of the vehicle acoustic device. You can get the effect that you can.

In addition, in order to reproduce the desired low frequency sound, only the diaphragm member is made of a material suitable for this low frequency sound reproduction, which is economically advantageous since there is no need to replace the entire panel member with a material made of such a material. sexuality is demonstrated.

Furthermore, according to an embodiment in which acoustic shields are installed on both sides of the panel member along the slit, in addition to the above-mentioned common effects, a decrease in the output sound pressure level due to the cancellation of out-of-phase sound waves in the low range can be prevented. The effect is that the low frequency characteristics can be improved.

[Brief explanation of the drawing]

Fig. 1 is a partially cross-sectional side view showing a portion of a driver for excitation in a conventional vehicular acoustic device, Fig. 2 is a plan view showing a conventional vehicular acoustic device, and Fig. 3 is a side view of a part of the driver for excitation in a conventional vehicular acoustic device. A side view, FIG. 4 is a characteristic curve diagram showing reproduction frequency characteristics of the same vehicle audio device, FIG. 5 is a plan view showing an embodiment of the vehicle audio device according to the present invention, and FIG. vx-
v+s sectional view, FIG. 7 is a characteristic curve diagram showing the reproduction frequency characteristics of the above vehicle audio device, FIG. 8 is a plan view showing another embodiment of the present invention, and FIG. 9 is IX-IX in FIG. 8. A line sectional view and FIG. 10 are characteristic curve diagrams showing reproduction frequency characteristics of another embodiment of the same. 8: Panel member 8a: Opening 9: Diaphragm member 11: Sleeves 112a, 12b: Acoustic shield D: Driver Clarion Co., Ltd. Nissan Motor Co., Ltd. agent Ashi 1) Nao Eri Figure 4 6 Varnish 77 Ward

Claims (1)

[Scope of Claims] 1. A hole having a required area is bored in a panel member such as a member for car interior interior, and a separate diaphragm member is supported by both opposing edges of the hole to fill the hole. A vehicle acoustic device characterized in that a driver for excitation is attached to one core motion plate member. 2 A patent in which a slit corresponding to the clearance for vibration is formed between the vibrating side edges of the diaphragm member and the opening, and acoustic shields are installed on both sides of the panel member along the slit. A vehicle acoustic device according to claim 1.