JPH0439839B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a speaker for audio equipment.

(Conventional configuration and its problems) Conventionally, there are devices that detect the amplitude, speed, acceleration, etc. of a vibration system in order to control a speaker.
In the present invention, a microphone is used to detect sound pressure generated from a vibration system. Conventional detection devices that use microphones have the advantage of being able to detect vibrations without contacting the vibration system, but in order to prevent the diaphragm from coming into contact with the microphone even if the diaphragm oscillates greatly, it is necessary to It was necessary to provide a microphone 2 in the center of the diaphragm 1 at a certain distance from the diaphragm 3. Therefore, the output signal of the microphone 2 is delayed in phase by the distance corresponding to the sound pressure reproduced by the speaker's diaphragm 3, and there is a time delay between the sound generation from the diaphragm and the sound wave front reaching the microphone. It was very difficult to freely control the speakers with a simple configuration as shown in Figure 3.

In particular, at high frequencies where there is a distance of one wavelength or more between the diaphragm and the microphone, the phase is 180°.
It was impossible to compensate for the time delay at higher frequencies.

In Fig. 1, 4 is a yoke, 5 is a magnet, 6 is a plate, 7 is a frame, 8 is a voice coil, 9 is a damper, 10 is a dry cone, 1
1 is edge.

(Objective of the Invention) An object of the present invention is to detect a signal that is accurately proportional to the sound pressure reproduced by a speaker, and to easily and accurately control the sound reproduced by the speaker.

(Structure of the Invention) The present invention provides a speaker with a flat diaphragm, in which a microphone is attached to the tip of a center pole, the center pole is extended in the main radiation direction of sound, and the microphone attached to the tip is moved near the center of the diaphragm. It is fixed.

(Explanation of Examples) Embodiments of the present invention will be described with reference to the drawings.

In Fig. 2, reference numeral 3 denotes a diaphragm of the speaker, which has a hole in its center, and the holder of the microphone 15 is placed in such a way that the diaphragm of the microphone 15 is in the same plane as the diaphragm in the hole. It is fixed to the top of the center pole 17. Subedge 16
This is to prevent the sound pressure of the speaker from going around to the back side of the diaphragm 3 of the microphone 15 at low frequencies.

With this configuration, the diaphragm of the microphone 15 is located near the acoustic center of the reproduced sound pressure of the speaker (the position where the phase of the applied voltage waveform of the speaker voice coil and the phase of the microphone output voltage waveform match), There is no longer a time difference between the reproduced sound pressure and the sound pressure detected by the microphone 15. In addition, since the wavelength is long at low frequencies, the sound pressure near the speaker diaphragm 3 is uniform, and the speaker diaphragm 3 and the microphone 15 diaphragm can have almost the same phase, so when controlling The phase compensation of can be realized with a minimum necessary simple configuration, and a system as predicted can be realized by simple calculations without the need for theoretically complicated simulation calculations.

Further, the directional characteristics of the microphone 15 depend on the frequency to be controlled, and may be directional if limited to low frequencies, but non-directional is preferable if high frequencies are included. Therefore, when limited to low frequencies, the directivity of the sound is weak, so the front surface of the microphone does not necessarily have to be oriented parallel to the direction in which the sound is radiated from the diaphragm of the speaker.

FIG. 3 shows an embodiment in which the detection signal of the microphone according to the present invention is fed back to the input side. If the gains of the power amplifier 12 and the feedback amplifier 14 are A and B, respectively, the feedback amount A×B is It is common knowledge that the linearity of

Further, in FIG. 3, other than providing a frequency characteristic at A or B to obtain the designed amount of feedback, there is no need for a correction circuit for correcting the distance/time difference between the microphone and the speaker as in the prior art.

Furthermore, according to the present invention, the sound radiation surface of the speaker, such as angle 1 in FIG. It can also be used to compose something excellent.

In the above embodiment, the case where the speaker diaphragm is a flat diaphragm is described, but even in a cone-shaped diaphragm 18 as shown in FIG. 4, the microphone 15 is attached on an extension of the center pole 17, A similar method can be achieved by placing the microphone 15 inside the dust cap 19 or outside the dust cap 19 by making a hole in the dust cap 19, and in any case placing the microphone 15 at the acoustic center of the sound reproduced by the speaker. Effects can be obtained.

Furthermore, it is desirable that the microphone be mounted in the direction of sound radiation, taking into consideration the phase at high frequencies.

(Effects of the Invention) According to the present invention, the phase of the sound pressure of the speaker diaphragm and the microphone diaphragm can be made the same.
Since it is possible to detect a signal that is accurately proportional to the sound pressure reproduced by the speaker, the effect is that it is extremely easy to control the sound reproduced by the speaker.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional speaker, FIG. 2 is a sectional view of a speaker according to the present invention, FIG. 3 is a feedback block diagram, and FIG. 4 is a sectional view of a speaker according to another embodiment of the present invention. It is. 1...Angle, 2...Microphone, 3...
Vibration plate, 4...Yoke, 5...Magnet, 6...
...Plate, 7...Frame, 8...Voice coil, 9...Damper, 10...Drive cone, 1
1... Edge, 12... Power amplifier, 13... Speaker, 14... Feedback amplifier, 15... Microphone, 16... Sub edge, 17... Center pole, 18... Cone-shaped diaphragm, 19... Dust Cap.

Claims (1)

[Claims] 1. In a flat diaphragm speaker, a through hole is provided in the center of the flat diaphragm 3, and a center pole 1
7 is extended in the main sound radiation direction and a microphone 15 attached to the tip thereof is fixed near the through hole of the plane diaphragm 3, and the output signal of the microphone 15 is fed back to the input of the speaker. speaker. 2. In a cone-shaped diaphragm speaker, a through hole is provided in the center of the cone-shaped diaphragm 18, and the microphone 15 is attached to the tip of the center pole 17 by extending it in the main sound radiation direction. A speaker fixed at an acoustic center near a through hole of a microphone 15, and an output signal of a microphone 15 is fed back to an input of the speaker.