JPH01189698A - Acoustic reflection panel - Google Patents

Abstract

PURPOSE:To prevent noise absorption from being generated due to primary resonance in a reflection panel by restraining the primary resonance of the reflection panel and reflecting the resonance with receiving an incoming acoustic wave and exciting the reflection panel at a real time with a reverse phase. CONSTITUTION:In the rear central part of a reflection panel 1 to use a conventional thin type and light reflecting plate, a compact oscillation acceleration meter 2 is fit as an oscillation meter. Thus, the oscillating waveform of the panel 1 is picked up and the phase is inverted by a phase converter 3 at the real time. Further, a signal is amplified by necessary quantity with using an amplifier 4 and after that, the signal flows to a moving coil 5 in a magnetic field, which is formed by a magnet 6, and driving force is generated. Then, the panel 1 to be united with this force is oscillated in the reverse direction of the oscillation which is generated by the incoming acoustic wave. Since the central part of the panel 1 goes to be the antinode of the oscillation in the primary resonance, the generated primary resonance can be suppressed by controlling the oscillation of this central part by the oscillation in the reverse direction. Then, the noise absorption factor in a resonance frequency area is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an acoustic reflective panel that constitutes the interior of a room such as a listening room or a musical instrument performance room where acoustic characteristics must be considered.

[Conventional technology]

When it comes to the interior of a listening room or musical instrument performance room, the acoustic characteristics of the room are adjusted by appropriately combining panels such as sound-absorbing panels and reflective panels, but the important thing is to adjust the reverberation time according to the purpose and the music being listened to. control of the absolute value of , and flattening the frequency characteristics of the reverberation time. The absolute value and frequency characteristics of the reverberation time of a room largely depend on the absolute value and frequency characteristics of the sound absorption coefficient of interior panels. In order to be able to freely control the absolute value of the reverberation time depending on the application or the music being listened to, it is necessary to use sound absorbing panels and reflective panels that are easy to install and replace, and to obtain a reverberation time with a flat frequency response. In order to achieve this, the frequency characteristics of the sound absorption coefficient of sound absorbing panels and reflective panels must be flat. If you have sound-absorbing and reflective panels that meet these conditions, you can easily control the acoustic characteristics of the room and avoid coloration of reverberant sound (sound coloration, where the frequency characteristics of the reflected sound differ greatly from the incident sound). , it is possible to create a room with high-level acoustic characteristics.

A conventional reflective panel 1, as shown in FIGS. 5 and 6, has reflective plates fixed at the upper and lower ends and is intended to reflect sound incident on the surfaces thereof. However, the normal reflective panel 1 must be movable so that the acoustic characteristics can be adjusted appropriately, and in that case, during construction, an air layer is often created between the reflective panel 1 and the wall behind it. This air layer acts as a spring, causing the plate to vibrate violently at a certain frequency (resonance frequency), which absorbs sound, but has the disadvantage that it does not reflect sound in that frequency range.

As a result, the frequency characteristics of the sound absorption coefficient are no longer flat, giving reflected sound a specific tone. In order to solve this problem, either make the reflective panel 1 thicker or create a larger air layer so that the resonant frequency becomes less important for listening to music.
00H2 or less, but in that case, the weight increases, making it difficult to move the reflective panel 1 appropriately to change the acoustic characteristics depending on the application, and if the thickness is large, it may be difficult to install it indoors. The smaller the room, the more problems arise.

[Problem to be solved by the invention]

In view of the above drawbacks, the present invention provides a thin and lightweight reflective panel that does not absorb large amounts of sound even at the primary resonance frequency of the reflective panel and has flat reflective frequency characteristics by actively controlling the vibration of the reflective panel. The purpose is to provide

[Means to solve the problem]

The gist of the present invention is to suppress the primary resonance of the reflective panel and reflect the input sound wave by collecting the sound waves incident on the reflective panel and exciting the reflective panel in real time with the opposite phase. This is a distinctive acoustic reflective panel.

The present invention uses a conventional thin and lightweight reflective plate to actively control the vibration of this reflective panel in response to incident sound, thereby preventing sound absorption due to the primary resonance of the reflective panel. It is something.

(Example 1) As shown in FIG. 1, a small vibration accelerometer 2 is attached as a vibration meter to the center of the back surface of a reflecting panel 1 made of appropriately selected metal, synthetic resin, wood, etc. suitable for reflecting sound waves. As a result, the vibration waveform of the reflective panel is obtained, its phase is reversed in real time by the phase converter 3, the signal is further amplified to the required magnitude using the amplifier 4, and then the vibration waveform in the magnetic field formed by the magnet 6 is inverted. Flow into moving coil 5,
A driving force is generated to vibrate the reflective panel 1 integrated with the driving force in a direction opposite to the vibration generated in the reflective panel 1 by the incident sound wave. In the case of this embodiment, even the small vibration accelerometer 2 and the moving coil 5 need only be integrated with the reflective panel 1.

In the primary resonance, the central part of the panel 1 becomes the antinode of vibration, so by controlling the vibration of this central part by reverse direction vibration, the primary resonance that conventionally occurs can be eliminated, as shown in the graph of Figure 4. As shown in the graph of FIG. 3, the sound absorption coefficient in the resonance frequency range decreases.

(Example 2) As shown in FIG. 2, a small microphone 7 is installed in front of the center of the reflective panel 1. As a result, the sound incident on the reflective panel 1 is collected, its phase is reversed in real time by the phase converter 3, the signal is further amplified to the required magnitude using the amplifier 4, and then the signal is formed by the magnet 6. The moving coil 5 in the magnetic field generates a driving force, which causes the reflective panel 1 integrated with the moving coil 5 to vibrate in the opposite direction to the vibration generated in the reflective panel 1 by the incident sound wave.

In this embodiment, even the moving coil 5 only needs to be integrated with the reflective panel 1.

〔Effect of the invention〕

As described above, the reflective panel of the present invention suppresses the vibration of the reflective panel caused by incident sound waves by applying a driving force of opposite phase to the center of the reflective panel, eliminates the sound absorption of the reflective panel due to primary resonance, and reflects the It is possible to absorb sound only by the material of the panel itself, resulting in a reflective panel with a low sound absorption coefficient, flat sound absorption frequency characteristics, and no coloration in the reflection characteristics.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of Example 1, Figure 2 is a cross-sectional view of Example 2, Figure 3 is a graph showing the frequency characteristics of sound absorption coefficients of Example 1 and Example 2, and Figure 4 is a graph of the conventional example. A graph showing frequency characteristics of sound absorption coefficient, FIG. 5 is a sketch of a conventional example, and FIG. 6 is a cross-sectional view of the conventional example. ■-Panel, 2-Small vibration accelerometer, 3-Phase converter,
4-Amplifier, 5-Moving Coil, 6-Magnet,
7- Small microphone.

Claims (3)

[Claims] (1) An acoustic reflection panel characterized by detecting the sound waves incident on the reflection panel and exciting the reflection panel in real time with the opposite phase of the sound waves, thereby suppressing the primary resonance of the reflection panel and reflecting the input sound waves. . (2) Attach a vibration meter to the center of the reflective panel, read the vibration waveform of the reflective panel when sound is incident, and generate a driving force by passing a current with the phase of the waveform reversed through the moving coil in the magnetic field, The acoustic reflecting panel according to claim 1, wherein the acoustic reflecting panel is configured to suppress primary resonance of the reflecting panel integrated therewith. (3) A microphone is installed in front of the reflective panel to pick up the incident sound, and a current with the phase of the waveform of the sound reversed is sent to a moving coil in the magnetic field to generate driving force and become integrated with this. The acoustic reflecting panel according to claim 1, which suppresses primary resonance of the reflecting panel.