JPS63272299A - On-vehicle acoustic reproducing device - Google Patents

Abstract

PURPOSE:To optimize the speaker installation position and to save the space by adding two audio signals being low frequency signal and delay signal by an adder and radiating it into the cabin from a speaker on a rear tray. CONSTITUTION:An audio signal is subjected to frequency band split into low frequency and middle/high frequency signals by a low pass filter means 6 and a middle/high pass filter means 7 respectively. Moreover, the high/middle signal is inputted to a delay means 8, the two audio signals of the low frequency signal and the delay signal are added by the adder means 9. The two audio signals are level-balanced by the ratio of the resistance of the two fixed resistors 13, 14. The sum signal added by an adder means 9 is amplified by a signal amplifier 3 and radiated in the cabin by the speaker unit 1 on the rear tray. Moreover, a drawn cone is provided in the acoustic tube 2 and it acts like an acoustic high-cut filter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a sound reproducing device mounted on a vehicle in a closed space such as a vehicle interior.

BACKGROUND OF THE INVENTION In recent years, as the performance of in-vehicle sound reproducing devices such as compact disc players has improved, there has been an increasing demand for expanding the range of low-frequency reproduction inside the vehicle to deeper bass. On the other hand, there is also a growing demand for realizing various sound fields by controlling the sense of distance and spread of sound images using reverberant sound even in small closed spaces such as passenger compartments. Against this background, there is a conventional vehicle interior sound reproducing device having a configuration as shown in FIG. 4, for example. In FIG. 4, 11 is a speaker unit for low frequency signals, 12 is a speaker unit for delayed signals, 3 is a signal amplifier, 4 is a rear cell, 6 is a trunk room, 6 is a low frequency filter means,
Reference numeral 7 represents a medium-high frequency filter means, and 8 represents a delay means. This conventional example has a system configuration in which a speaker unit 12 is separately provided for reproducing delayed signals.

Problems to be Solved by the Invention However, in the conventional configuration shown in FIG. 4, in order to reproduce the delayed signal, a reproduction system consisting of an additional signal amplifier, speaker unit, etc. There were problems with securing space and the high cost of equipment.

In view of the above problems, the present invention provides an in-vehicle sound reproduction device that radiates a low frequency signal and a delayed signal into a vehicle interior using a single speaker unit without increasing the number of reproduction systems for reproducing delayed signals. be.

Means for Solving the Problem In order to achieve this object, the in-vehicle sound reproducing device of the present invention includes a low-pass filtering means for filtering the low frequency band of the audio signal, and a filtering means for filtering the middle and high frequency band. The output signal of the adding means is converted into a signal. The configuration is such that the signal is applied via an amplifier to a speaker with an acoustic tube on the back.

Effect The present invention has the above-mentioned configuration, so that two signals, a low frequency signal and a delayed signal, can be used.
The two audio signals are added together using an adder and then radiated into the vehicle interior through the speakers on the rear tray, resulting in cost and space savings compared to adding a signal amplifier, speaker unit, or other reproduction system to reproduce delayed signals. Furthermore, since the speaker can be installed at any position on the rear tray, the installation position can be designed to be the optimum position on the rear tray in terms of acoustic characteristics.

For low-frequency signal reproduction, the resonance of the acoustic tube is used to increase the sound pressure level, and for delayed signal reproduction, a drone cone installed inside the acoustic tube acts as an acoustic high-cut filter, and here the delayed signal is It can also be significantly attenuated.

Therefore, the delayed signal uses only the sound radiated from the front of the speaker and eliminates interference with the sound from the acoustic tube, and the bass enhancement effect of the acoustic tube for the entire speaker system is the sound pressure of the delayed signal due to interference up to the trench. Disturbances in characteristics can be improved.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an in-vehicle sound reproduction device and its installation position in an embodiment of the present invention, FIG. 2 is a schematic side view, and FIG. 3 is a top view of the same.

In Figures 1 to 3, 1 is a speaker unit, 2 is a sound tube, 3 is a signal amplifier, 4 is a rear tray in the passenger compartment, and 5 is a speaker unit.
1 is a trunk room, 6 is a low-pass filtering means, 0 is a medium-high frequency filtering means, 8 is a delay means, 9 is an addition means, and 10 is a drone cone.

The operation of the in-vehicle sound reproducing device configured as described above will be explained below.

The audio signal is frequency band-divided into a low-frequency signal and a medium-high frequency signal by the low-pass filtering means 6 and the middle-high-pass filtering means 6, respectively. Furthermore, the middle and high frequency band signals are input to delay means 8, and the two audio signals, the low frequency signal and the delayed signal, are added by addition means 9. The level balance between the two audio signals is determined by the ratio of the resistance values of the two fixed resistors 13 and 14 in FIG. Next, adding means 9
After the added signal is amplified by the signal amplifier 3,
It is radiated into the vehicle interior by the speaker unit 1 on the rear tray.

If the speaker unit 1 has an acoustic tube 2 on its back and its length is half the wavelength of the resonant frequency, then the acoustic tube 2
Since the sound from the opening has a phase delay equivalent to a half wavelength, it becomes in phase with the sound from the front of the speaker unit 1, and by combining it with this, the bass can be enhanced and radiated into the vehicle interior.

However, in this state, the delayed signal is also emitted from the back of the speaker unit 1 through the acoustic tube 2, so it interferes with the sound from the front of the speaker unit 1 in a complicated manner.
As shown in FIG. 6, this deteriorates the sound pressure characteristics and deteriorates the sound quality of the delayed signal.

In contrast, a drone cone is provided in the acoustic tube 2 and operates as an acoustic high-cut filter.

FIG. 7 shows the distribution of sound pressure and particle velocity generated within the acoustic tube. In Figure 7, the sound pressure is maximum at the position where the particle velocity is zero, and the acoustic impedance 2□-P/U at that time is theoretically infinite, so if Dronco 710 is placed at this position, For example, since the impedance of the drone cone 1o is negligible, a decrease in the sound pressure level due to the presence of the drone cone 10 can be eliminated. In this embodiment, the position of the drone cone 10 is at approximately A of the total length of the acoustic tube, and at frequencies below 2Fo=F, the necessary bass can be reproduced with minimum attenuation. On the other hand, at frequencies above 4Fo=F, the impedance and actance component ωMD (ω: angular frequency, mass of the MD nitron cone) of the drone cone 1o cannot be ignored, and it acts as an acoustic high-cut filter, and can be used as a speaker system. The sound of the delayed signal emitted is only the sound from the front of the speaker unit 1, and as shown in FIG. 8, disturbances in the sound pressure characteristics of the delayed signal can be greatly reduced.

Effects of the Invention As described above, according to the present invention, two audio signals, the output of the low-pass filtering means and the output of the delaying means, are added by the adding means, and the speaker system is configured such that one unit of the speaker unit is added. By constructing a sound tube with a drone cone inside on the back, the bass enhancement effect due to resonance of the sound tube remains unchanged in a single speaker unit installed on the rear tray, and the sound from the front of the speaker unit and the sound tube are The sound pressure characteristics of the delayed signal are not disturbed due to interference with the sound from the opening, and the sound pressure characteristics of the delayed signal can be radiated into the passenger compartment from the optimal position for acoustic characteristics on the rear tray. This makes it possible to realize an excellent in-vehicle sound reproduction device that can save cost and space.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an in-vehicle sound reproduction device according to an embodiment of the present invention and its installation position in the vehicle interior, Fig. 2 is a side view of the same, Fig. 3 is a top view of the same, and Fig. 4 is a conventional car sound reproduction device. A perspective view showing the room sound reproducing device, FIG. 6 is a circuit diagram of the adding means, FIG. 6 is a sound pressure-frequency characteristic diagram when no drone cone is provided in the acoustic tube, and FIG. 7 is a diagram showing the sound pressure and frequency characteristics in the acoustic tube. Particle velocity distribution characteristic diagram, Figure 8 shows the sound pressure when a drone cone is installed in the acoustic tube.
It is a frequency characteristic diagram. 1... Speaker unit, 2... Acoustic tube, 3... Signal amplifier, 4... Rear tray, 5... Trunk room, 6...・・・・・・
Low-pass filter means, 7...Mid-high pass filter, 8...
...delay means, 9...addition means, 10...
...Drone cone, 11...Speaker unit for delayed signal, 12...Speaker unit for low frequency signal. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
Sudo-〃-Unit 2-Acoustic tube 3-Signal jt Tsuruhiro 4-Rear tray 5-Trunk room 6...-Low Makoto RonJAhiro 7-Medium and high range Ryokan 8-Different R 9--- mx+stage to-F-Roncorn No. 1rllJ o-(G Fig. 6

Claims (3)

[Claims] (1) A low-pass filtering means for filtering a low-frequency band of an audio signal, a middle-high-pass filtering means for filtering a middle-high frequency band of the audio signal, and a delay in the output of the middle-high-pass filtering means. and an addition means for adding the output of the low-pass filtering means and the output of the delay means, and applying the output signal of the addition means to a speaker having an acoustic tube on the back side through a signal amplifier. An in-vehicle sound reproduction device characterized by: (2) The speaker is formed by a single speaker unit,
2. The vehicle-mounted sound reproducing device according to claim 1, wherein the speaker radiates the output signal of the adding means into the vehicle interior. (3) The vehicle-mounted sound reproducing device according to claim 1, wherein the acoustic tube has a drone cone provided therein.