Next, let's consider what kind of speakers are good speakers that can reproduce bass beautifully. First, we will consider problems of current speakers.
Since the diaphragm of the current speaker has a structure that reciprocates, the sound coming out in front of the unit and the opposite phase sound going backwards of the unit cancel each other out, especially the low sound weakens.
Even with popular woofer units, the frequency below 100 Hz to 200 Hz will gradually decrease in level, so you need to install it in a bass reflex type box and sound the box to reinforce the bass.
As a result, it is impossible for playback of the bass by all means. It is necessary to develop a unit which can easily reproduce from the beginning from about 30 Hz even if it is not installed in a box.
Let's review the principle of sound from the basics for those reasons.
Flexural vibration is the most effective way to produce natural sound
For example, all sounds emitted from natural objects, such as sounds of shoes, sounds when hitting a desk, piano sounds, contrabass sounds, are caused by deflex vibration of the surface.
On the other hand, the sound of an ideal speakers is said to be the sound of a spherical wave emanating from a point sound source. If there is an ideal point sound source, its surface is Flexural and vibrating.
That is, if you are trying to make a speaker that produces the same ideal sound as it is in nature, it means that the diaphragm should be worked with Flexural vibration not piston vibration.
It is possible to think that a spherical wave is composed of a small plane wave, but to reproduce it it is impossible with a single previous piston oscillating unit generating a plane wave, and we have to combine a myriad of previous piston oscillating unit.
So, of course, there are many patents and ideas of speakers that use flexual vibration from various manufacturers in japan. EX.1 Transverse wave speaker The transverse wave speaker made by Prof. Mutoh, Keio University.
The main parts of this system, unit 24, diaphragm plate 1, fixing device 31, and body 1, are connected in-line and forms the HIZUMI vibration producing system. However, diaphragm plate 1 is bending and unnaturally loading the dumper 23. Therefore, there is a fear of not fixing and working stable operation.
Reference PN 2007 – 19623
EX.2 Magnetic circuit HIZUMI element speaker
Sony’s magnetic circuit HIZUMI element speaker. (State of driving rod abuts to diaphragm plate)
Fig. shows the example of HIZUMI vibration speaker using magnetic circuit HIZUMI actuator 110 and producing HIZUMI movement to diaphragm plate 130.。
The moving part 110a is connected directly to diaphragm plate 130, and the body 100 is also connected to the same diaphragm 130. These parts are connected in-line and forms later explained HIZUMI vibration producing system, however, magnetic circuit HIZUMI actuator does not give output to release sound large enough into air.
Fig. shows; Transmission material 202, equivalent of driving part of voice coil driver is directly connected to diaphragm plate 203 and this diaphragm plate 203 is connected firmly to flame 201, the body. This forms the HIZUMI vibration producing system like A and B
However, in this structure, the diaphragm plate 203 which is connected by tube 204, flange 205 and again flange 205 are united as one. Therefore, this part also moves back and forth which leads to loss of vibration energy.
Reference PN 2010 – 283565
EX.4 Teragaki speaker
An experiment in which vibration of a music box vibrates a piece of paper through a stick and produces a sound.
He says, "The sounds in nature change their vibrations into sounds in this way."
Teragaki Speaker's principle is that the paper piece is not a parallel reciprocating vibration, but works with the deflex vibration.
However, deflex vibration, that is, natural vibration, can sound natural sound in terms of sound quality, but it has not been possible to obtain good frequency characteristics until now for any deflex vibration speakers.
In order to solve this problem I discovered that using the principle invented by Edison makes it possible. With this we will be able to make ideal speakers that work with flexural vibration.
The diaphragm of sound box invented by Edison had a structure that the center was connected with a point, and it became speakers to be driven by a point.
If it is operated by deflex vibration with point drive instead of operating with piston motion unlike the conventional speakers, it becomes easy to produce the sound of the diffused wave having better frequency characteristics.