JPS58218296A - Audio device for vehicle - Google Patents

Abstract

PURPOSE:To prevent a peak and dip from being generated in a reproduction frequency characteristics, by attaching a viscoelastic member for suppressing a natural oscillation of a damper to the damper to prevent a diaphragm from vibrating with the natural frequency of a damper beam part. CONSTITUTION:A viscoelastic member 21 for suppressing a natural oscillation of a damper 6 is attached to the surface part of the damper 6. If a sound signal is inputted in a coil 13, a magnet side 4 and an exciting plate side 3 displace and oscillate relatively through the damper 6, and a diaphragm 16a is excited with the oscillation of the exciting plate 3, etc., to reproduce a low sound range. The beam of the damper 6 tends to oscillate due to its natural frequency. However, the oscillation is absorbed and damped by the viscoelasticity of the viscoelastic member 21 to suppress the generation of oscillation to the outside. As a result, a peak and dip of a frequency part corresponding to the natural frequency of the beam is almost eliminated in a reproduction frequency characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle acoustic device that is attached to a rear parcel shell 7 or the like of an automobile and uses a panel member constituting the rear parcel shell 7 or the like as a diaphragm. □ Examples of conventional vehicle acoustic devices include those shown in Figures 1 to 4 (Japanese Patent Application No. 150119/1982).
. First, FIGS. 1 and 2 show an excitation driver 0, in which a cover plate (2) is fixed to the rear end surface of a cylindrical frame (1) to form a housing.

Further, a vibration plate (3) is fixed to the front end surface to constitute a case body.

The yoke (5) equipped with an annular magnet (4) is pressed so that it is located in the center of the case body, and the damper (
6) is elastically supported by the frame 11).

The yoke (5) consists of a pole piece (7) with a bottom plate (7) at the rear end and a yoke plate (8). A magnet (4) is sandwiched between the magnet (7m) and the magnet (4), which together form a magnetic circuit having an annular gap (9). The damper (6) is formed into a ring shape with an elastic plate made of stainless steel or the like with an appropriate thickness, and its inner peripheral edge is fixed to the yoke plate (8), and its outer peripheral edge is a step on the frame (1). It is appropriately fixed to the portion (1a). As shown in FIG. 2, this damper (6) is provided with double arc-shaped slits (6 m) and (6 b) at appropriate intervals. Inside three / ) (6m) and outside =su・'t'N (6b
) means each inner <su・to (6・), (6・) punctuation i
：″The center part of each outer space □11 (61) is bored alternately in the circumferential direction in a positional relationship similar to that of the damper (6). is the length t where this inner slit (61) and the outer slit (6b) intersect,
As will be described later, it acts as a beam (6c) for elastic support.

On the other hand, a round hole of a required diameter is bored in the center of the vibration plate (3), and a bobbin a extending to the cavity (9) is fixed to the round hole. A coil a3 is wound around the bobbin αa at a portion located in the gap (9), and a voice coil is formed by the coil Q3 around the bobbin a. The vibrating driver D configured in this way is attached to the rear parcel shelf 6 as shown in FIGS. 3 and 4.
The frame (1) is attached to the back side of the diaphragm (16 m) constituting the diaphragm 9 by screws or the like.

゛Then, when the voice signal is energized by 1□ to the coil Ql through the input terminal, the Agennet (4) side and the Frame Ro), that is, the excitation grating (3) side, undergo relative displacement vibration, and this occurs.
!・11. ] Vibration play) (3) The diaphragm (tea) is vibrated by the vibration #, and the low frequency range is reproduced.

By the way, such a vehicle audio device is a suitable speaker because it can reproduce a much lower bass range than other speakers such as a cone speaker.

The lowest resonant frequency fo depends on the spring constant of the beam (6C) in the damper (6).
It is known that this spring constant is expressed by the following 0 formula.

n: number of beams (6c), IC: Young's modulus, ■: section modulus of beam, 1 + length of beam ゛ Therefore, taking advantage of the characteristics of this type of vehicle acoustic device, for example! In order to shift the reproduction range to a much lower frequency side such as 00 Hz, it is necessary to lower the spring constant K expressed by the above equation 0.

On the other hand, it is known that the natural resonance frequency f (n) of the beam (6C) portion is expressed by the following equation 0.

ρ: Density of material constituting the beam, A: Cross-sectional area of the beam *k(
n); The eigenvalue determined by the resonance conditions and the beam (6c) is this natural resonance frequency? f(n
) to vibrate independently.

However, in such a conventional vehicle acoustic device, the damper (6) is made of an elastic plate such as stainless steel, and its inner and outer edges are connected to the yoke plate (8) and the frame (1). Because the vibration of the beam (6C) at the natural resonant frequency An> peaks (19
a), which appears as a dip (19b) during playback output. Then, in order to shift the reproduction range to an even lower frequency side, if the beam length t is changed from the above formula 0 to lower the spring constant K, the spring constant K is lowered by changing the beam length t. From the formula, the natural resonance frequency f(n) is also low, with peak (19m) and dip (19m) in Figure 5.
b) is shifted to the left side, resulting in a problem that the reproduction frequency band B in which the low frequency range can be properly reproduced is narrowly limited. Furthermore, when harmonics of a frequency signal lower than this natural resonance frequency f(n), such as f(n)/2, match the natural resonance frequency f(n), harmonic distortion may be emphasized. However, there is a problem in that the distortion rate in the bass reproduction range also increases.

The present invention has been made in view of these conventional problems, and aims to solve the above problems by adding a viscoelastic member to the damper for suppressing natural vibrations.

The present invention will be explained below based on the drawings. FIGS. 6 and 7 are diagrams showing a first embodiment of the present invention. In each of the figures from FIG. 6 onwards, the same or equivalent members or parts as in FIGS. 1 to 4 are designated by the same reference numerals and redundant explanations will be omitted.

i′・ First, to explain the configuration, in this invention the damper (
6) A viscoelastic member Qυ for suppressing the natural vibration of the beam (6c) of the damper (6) is attached to the surface of the damper (6). For example, a rubber plate with a thickness of about 2 mm is used as the Viscoelastic Member Co., Ltd. In the example shown in FIG. 7, the viscoelastic member Qυ is pasted to the parts other than the perforated parts of the slits (6a) and (6b). It may also be pasted on the entire surface of the damper (6). Further, the viscoelastic member C11l may be attached to the back surface of the damper (6).

Next, the action will be explained. When the audio signal is energized to the coil Q, the magnet (4) side and the excitation plate (3) side are relatively displaced and vibrated via the damper (6), and the second excitation plate (3) ) etc., the diaphragm (16m) is vibrated to reproduce the low frequency range. At this time, the damper (
6), the beam (6C) has its natural resonant frequency f(n)
This vibration tends to occur in the viscoelastic member Q1.
) is absorbed by the viscoelasticity of the stone and is braked to prevent the formation of □ to the outside. : Therefore, as shown in Fig. 8, due to the reproduction frequency characteristics, the natural resonant frequency f(
The peaks and dips in the frequency portion corresponding to n) are almost eliminated, and the reproduction frequency band B' in which the low frequency range can be properly reproduced is expanded. Also, the natural resonance frequency f(n
), harmonic distortion is not emphasized even if the harmonics of a lower frequency signal match the natural resonance frequency f(n).

Next, FIG. 9 shows a second embodiment of Jin's invention.

In this example, the viscoelastic member (2) is
It is interposed between the outer peripheral edge of the frame (1) and the step (1a) of the frame (1). In this example, the beam (6C)
The vibration at the natural resonant frequency f(n) of
Transmission to a) is suppressed. Therefore, the above figure 8 and #
? Improved reproduction frequency characteristics similar to Ett can be obtained.

Next, FIG. 10 shows a third embodiment of the present invention.

In this embodiment, a viscoelastic member (c) is interposed between the inner peripheral edge of the damper (6) and the yoke plate (8). In this embodiment, the vibration at the natural resonant frequency f(n) of the beam (6C) is absorbed by the viscoelastic member (c) interposed in the inner peripheral edge attachment part, and the transmission of the vibration plate (16m) is suppressed. . The manner in which the frequency characteristics are improved is the same as in the second embodiment.

In each of the first to third embodiments, the viscoelastic member on,
cps, (c) are attached to the surface of the damper (6), interposed to the outer circumferential edge attachment portion, and interposed to the inner circumferential edge attachment portion, but this invention The present invention is not limited to the case where each of the attachment modes is different, and any two or three of the three attachment modes described above may be implemented at the same time. When such two-current or three-current application mode is used in combination, the frequency characteristics and harmonic distortion rate can be further improved.

As detailed above, according to the present invention, since a viscoelastic member for suppressing the natural vibration of the damper is attached to the damper,
The diaphragm is prevented from vibrating at the natural resonant frequency of the damper beam, and the effect is obtained that almost no peaks or dips caused by this vibration occur in the reproduction frequency characteristics. Therefore, even if the dimensions of the beam portion of the damper are changed to shift the lowest resonant frequency to a much lower frequency side, the bass reproduction range that can be properly reproduced will not be limited, and the characteristics of the vehicle acoustic device can be fully maintained. The effect of being able to exhibit the power of the human body is obtained. Further, it is possible to obtain the effect that harmonic distortion can be prevented from occurring in the bass reproduction range.

[Brief explanation of drawings]

Fig. 1 is a partially cross-sectional side view showing a portion of a driver in a conventional vehicle audio system, Fig. 2 is a partially cutaway plan view of a portion of the same driver, and Fig. 3 shows a conventional vehicle audio system installed in a car's interior. Fig. 4 is a cross-sectional view taken along the mV-IV line in Fig. 3, and Fig. 5 is a special diagram showing the reproduction frequency characteristics of Mongoro's vehicle acoustic device.
FIG. 6 is a partially sectional side view showing a portion of the driver in the first embodiment of the vehicle acoustic device according to the present invention; FIG. 7 is a partially cutaway plan view of the driver in the first embodiment of the same as above; FIG. 9 is a characteristic diagram showing the reproduction frequency characteristics of the vehicle acoustic device according to the present invention, FIG. 9 is a partially sectional side view showing the second embodiment of the invention, and FIG. 10 is a diagram showing the third embodiment of the invention. It is a partially sectional side view shown. 1: Frame (housing) 3: Vibration plate 4: Magnet 5: Yoke
6: Damper 6m, 6b Nislit 6c
: Beam 7: Ball piece (voice coil) 8: Yoke □ Rate 13: Coil 16a: Vibration plate... □ 21.22.2 Gij: Viscoelastic member D: Driver □-, 111, □°″1 Clarion Stock Company Nissan Motor Co., Ltd. Agent Ashi 1) Naoe Figure 1 Figure 3 Old Figure 4 Figure 5 FIH2I - Figure 6 Figure 7 F (H2I ~

Claims (1)

[Scope of Claim] A vehicle acoustic device comprising: a yoke provided with a magnet; a damper supporting the yoke in a housing; and a voice coil formed on a diaphragm side facing the yoke. A vehicle acoustic device characterized in that a viscoelastic member for suppressing the natural frequency of the nuclear damper is attached to the damper. 2. The vehicular acoustic device according to claim 1, wherein the viscoelastic member is attached to the damper. 3. The vehicle acoustic device according to claim 1 or 2, wherein the viscoelastic member is interposed and attached between the damper and the frame. 4. The vehicle acoustic device according to claim 1', 2, or 3, wherein a viscoelastic member is interposed and attached between the damper and the yoke.