JPH0422296A - On-vehicle speaker system - Google Patents

Abstract

PURPOSE:To easily obtain reproduction of ultralow pitched sound in a compartment by providing an open hole or a duct to a wall face of a door of an automobile toward its compartment so as to form the compartment like a speaker cabinet of bass reflex structure. CONSTITUTION:A sound wave radiating from a speaker 2 fitted to a front door 1 is roughly classified into a sound wave radiating to the front side of a diaphragm of the speaker 2, that is, a sound wave radiating to the outside of the door and a sound wave radiating to the rear side of the diaphragm of the speaker 2, that is, a sound wave radiating to the inside of the front door 1. The sound wave radiating from the speaker 2 in the inside of the front door 1 propagates through the internal space of the front door 1, reaches a bass reflex open hole 3, and radiates in the compartment at the outside of the door from the bass reflex open hole 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an in-vehicle speaker system that reproduces sufficient deep bass when audio is reproduced from a car stereo or the like in the interior of an automobile.

[Conventional technology]

Conventionally, as shown in FIG. 7, in the interior of a car, an audio reproduction speaker 2 is attached to the front door 1.
The volume inside the front door 1 is used to reproduce bass sounds. In this method, the passenger can hear the loudspeaker 2.
It has the advantage of being able to reproduce natural bass that can be heard from the front. However, the front door l has mechanical parts inside the door,
Working hole 6a for repairing and maintaining electrical parts
~6C is provided.

[Problem to be solved by the invention]

Conventional car-mounted speaker systems are as described above, so in the deep bass range, the sound waves of opposite phase emitted behind the speaker propagate through the space inside the front door, leak through the working hole, and are emitted from the front of the speaker. There was an issue with the ability to cancel out the sound waves emitted by the system, making it impossible to reproduce deep bass tones adequately.

Since this working hole is provided near the speaker or in the center of the door with emphasis on workability, it tends to cause cancellation of sound waves.

Furthermore, even if the working opening is closed to create a closed cabinet, there are problems such as the inability to reproduce sufficient deep bass sounds due to the small volume inside the door.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a vehicle-mounted speaker system that can reproduce deep bass sounds that can be heard from the front with sufficient sound pressure.

[Means to solve the problem]

In the vehicle-mounted speaker system of the present invention, an opening or a duct is provided in the door of an automobile to which a speaker is attached so as to form a phase-inverted structure.

[For production]

The in-vehicle speaker system of the present invention reverses the phase of the sound wave emitted from the speaker to the inside of the door in the deep bass band through an opening or a duct, so that it is in the same phase as the sound wave directly emitted from the speaker to the outside of the door. Increases sound pressure in the bass range.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows the appearance of the right front door of an automobile from inside the cabin. FIG. 2 is a schematic cross-sectional view of the front door. In FIGS. 1 and 2, 1 is a front door, 2 is a speaker installed on the wall of the lower half of the front door 1 on the side of the passenger compartment, and 3 is a speaker installed on the wall of the front door 1 on the side of the passenger compartment of the front door. 1 is a bass reflex hole having a phase inversion type (bass reflex; Ba5s-Reflex) structure, and 4 is a window glass. In this embodiment, an example is shown in which the speaker 2 and the bass reflex aperture 3 are separated from each other in the front and back of the front door 1 and are located directly next to each other.

The sound waves radiated from the speaker 2 attached to the front door 1 are divided into two types: one in front of the diaphragm of the speaker 2, and therefore to the outside of the door, and the other, the sound wave radiated to the rear of the diaphragm of the speaker 2, and therefore inside the door. Broadly classified. The sound waves emitted from the speaker 1 into the interior of the front door 1 propagate through the interior space of the front door 1, reach the bass reflex aperture 3, and are radiated from the bass reflex aperture 3 into the vehicle interior outside the door.

The operation at this time is known from the known literature; Acoustic Engineering [Volume 1] translated book,
Published by Radio Operator Education Association, 1959 edition, 191 pages, r
6-12, Phase Inversion Speaker" is represented by an equivalent circuit shown in FIG. 3 together with a schematic cross-sectional view of the front door. In Figure 3, mc is the mass of the diaphragm and voice coil, co is the compliance of the support, r□ is the mechanical resistance of the support plate, m^ is the mass of the air load, rNA is the mechanical resistance of the air load, and CIIV is the door. Internal compliance, mL
is the additional mass of the bass reflex hole 3, r□ is the mechanical resistance of the air load on the bass reflex hole 3, and f7 is the driving force generated in the voice coil. When circuits (2) and (2) in the equivalent circuit have positive mechanical reactance and no mechanical resistance, and furthermore, circuit (2) has pure compliance, the phase difference in speed with circuit (2) can be set to 180 degrees. Therefore, since the velocities on both sides of the diaphragm of the speaker 2 have a phase difference of 180°, this phase difference can be eliminated.

The compliance CMV inside the front door 1 and the additional mass m□ of the bass reflex aperture 3 resonate at a specific frequency due to Helmholtz resonance, and sound is radiated from the bass reflex aperture 3 to the outside. This frequency (anti-resonance frequency) is expressed as follows. The compliance C1,/ inside the door is determined from the internal volume of the front door 1. Compliance C□ is obtained from a value obtained by approximately measuring the door volume by a known means, and the relationship between antiresonance frequency f and additional mass mL can be specified from equation (1).

Desired anti-resonance frequency f from the relationship in equation (1) above.

It is possible to know the additional mass corresponding to , and determine the shape of the bass reflex aperture 3 having that additional mass.

Although only the bass reflex hole is shown in Figures 2 and 3,
As shown in a schematic cross section of the front door in FIG. 4, a straight duct 5 may be provided inside the front door 1 in the bass reflex opening. In this case, the duct diameter and duct length may be adjusted so as to satisfy equation (1) as described above.

An example of calculation for a speaker with a diameter of 16aI is shown below.

The constant of this speaker is expressed by the following equation (2).

Compliance C□ inside the door is given by the door volume V, C CIIv” ρ.
``' +31 However, ρ is the air density and C is the speed of sound.

The additional mass m, is the duct cross-sectional area S, and the duct length! , it is expressed as ′・・・・(4) ml・ρ・・(πa′)′・−ri1.

From the above equations (1) to (4), tan = (Sat)', q- 8, 2□ rl, , -(sl) 0 The front door volume of the passenger car is approximately 541, and the anti-resonance frequency is 1. Assuming 50 Hz, if the duct diameter is 2 to 20 ports, it is understood that the duct length may be selected within the range of approximately 0.6 to 70 mm.

FIG. 5 each shows a schematic cross section of the front door, and the same parts as in the first embodiment are given the same reference numerals 1 to 3 to avoid redundant explanation. Automobile doors have a shallow depth, making it difficult to install long ducts.

In this case, as shown in FIG. 5 18+, bend the duct to the required length and insert the duct 5a inside the front door 1 from the bass reflex opening 3 toward the speaker 2 side so that it can be easily stored in an L-shape. Even if it is provided, the same effects as in the above embodiment can be achieved.

Fig. 5 (bl shows the inner wall 1a of the front door 1
This is an example in which the duct 1-5b is shared with the inner wall of the front door 1 and extends from the bass reflex opening 3 toward the speaker 2 side inside the front door 1.

FIG. 3(C) shows an example in which a straight duct 5c is provided to protrude outside the front door 1.

FIG. 5 18+ shows an example in which an L-shaped duct 5d is extended from the bass reflex opening 3 toward the speaker 2 on the outside of the front door 1.

FIG. 5 18+ shows how the outer wall 1b of the front door 1 is connected to the duct 5.
This is an example in which the duct 5e is shared with the inner wall of the duct 5e and the duct 5d is provided in the same manner as the duct 5d.

FIG. 6 shows a schematic cross section of the front door, and is an example using a U-shaped duct. In FIG. 6, a U-shaped duct 5f is provided with the bass reflex aperture 3 in the center and extends toward the speaker 2 inside and outside the front door 1, and the inner wall 1a and the outer wall 1b of the front door 1 are connected to the inner wall of the duct 5f. It was designed to be shared with By deforming the duct in this manner, the duct can be efficiently housed in a narrow space such as the interior of a vehicle.

Note that even if a duct is provided as shown in FIGS. 5 and 6, the same effect as described with reference to FIG. 4 can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, an opening or a duct is provided on the side wall of the vehicle door and is configured like a speaker cabinet with a noxleaf structure, so that sufficient deep bass can be produced inside the vehicle interior. It has a regenerative effect.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the appearance of a front door according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of FIG. 1, and FIG. 4 is a schematic cross-sectional view of the front door showing the cross section of the duct forming the bass reflex structure, and FIG. A schematic cross-sectional view of the door, FIG. 7, is a diagram showing the appearance of a conventional front door.In the figure, 1...front door, 2...speaker, 3...
...bass reflex hole, ...duct. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] An in-vehicle speaker characterized in that a speaker is attached to the wall surface of the vehicle door on the side of the vehicle interior, and an opening or a duct is provided in the wall surface of the vehicle interior of the door to create a phase inversion type structure that utilizes sound from the rear surface of the speaker. system.