JPS5990495A - Speaker device - Google Patents

Abstract

PURPOSE:To apply MFB without deteriorating the efficiency of a speaker and giving any effect on the freqeuncy characteristic by providing a hole at the center of a diaphragm of a tweeter and providing a feedback microphone in the hole so as to detect the vibrating characteristic of the speaker in contactless with the diaphragm. CONSTITUTION:The hole 6a is provided at the center of a flat diaphragm 6. The microphone 5 is arranged in the hole 6a, and a cable 5a of the microphone 5 is led out through a pipe 12. When a nondirective microphone is used for the microphone 5, the sound pressure reproduced by the diaphragm 6 is detected almost at the effective acoustic center to minimize the phase difference between the detected signal of the microphone 5 and the sound source by the diaphragm 6, allowing to detect the sound radiated from the diaphragm 6 with fidelity.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a speaker device.

Conventional configuration and its problems Conventional speakers have motion feedback C or lower MF
B), a vibration detector 3 is attached to the speaker unit 2 as shown in FIG. 1, and its detection signal is fed back to the inverting input of the power amplifier 1. However, when the vibration detector 3 is attached to the diaphragm of the speaker unit 2, the vibration characteristics of the speaker unit 2 change. Especially in the case of high-pitched speakers, heavy equipment in the vibration system is very light, so the weight when the detector 3 is attached changes. The large increase causes a significant drop in efficiency, and furthermore, a sharp resonance peak occurs at the high acid detection limit frequency of detector 3, resulting in a large phase shift, making it impossible to apply feedback to the high-frequency speaker. It had been.

OBJECTS OF THE INVENTION An object of the present invention is to provide a speaker device that can apply MFB to a high-pitched speaker without causing the above-mentioned problems.

Structure of the Invention According to the present invention, a hole is provided in the center of the diaphragm of a treble speaker, and a feedback microphone is provided in this hole.

This prevents the microphone from coming into contact with the diaphragm, causing the above problem, and allows the MFB to be placed on the high-pitched speaker.
can be applied.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention is shown in FIGS. 2 to 4. In other words, Figure 2 shows a high-pitched speaker (hereinafter referred to as a tweeter).
A hole 6a is provided in the center of the flat diaphragm 6,
The microphone 5 is placed in the hole 6a, and the microphone 5 is placed in the hole 6a.
The output cable 5a is taken out through a pipe 12. 7 is an edge, 8 is a frame, 9 is a trough plate, 10 is a magnet, 11 is a yoke, and 13 is a voice coil. With this configuration, microphone 5
If it is an omnidirectional microphone, the sound pressure reproduced by the diaphragm 6 will be detected almost at its acoustic center, and the phase difference between the detection signal of the microphone 5 and the sound source produced by the diaphragm 6 can be minimized. , the sound radiated from the diaphragm 6 can be detected faithfully.

FIG. 3 is a block diagram of an MFB using this Rai-Tag. When the output signal of the microphone 5 is fed back to the inverting input of the power amplifier 1 via the feedback circuit 4, so-called acceleration feedback is applied, and after the feedback, the MFB As a result, the lowest resonant frequency (fo) of the tweeter 2' is lowered, and the distortion of the tweeter can be reduced by the amount of feedback.

FIG. 4 shows sound pressure frequency characteristics showing this situation, where the characteristic before return is a solid line a, and the characteristic after return is a broken line a. This diagram is
This is actual measurement data obtained by applying MFB to the tweeter 2', which has a flat diaphragm 6 with a diameter of 2.8 cIn, and measuring the sound pressure near the tweeter axis. Below s 5.5 KHz, negative feedback occurs, and the lowest resonant frequency is 2 KHz. The frequency has decreased from 1.6kHz to 1.6KHz. Further, the reason why positive feedback occurs below 5 kHz is because the phase of the sound reproduced by the tweeter 2' is rotated by more than 180 degrees relative to the input signal of the speaker. I wanted to,
Naturally, as the high frequency reproduction limit frequency of the tweeter 2' increases, the high frequency limit to which negative feedback can be applied also increases. Furthermore, it has been confirmed using the finite element method that providing a hole in the center of the diaphragm increases the rigidity of the diaphragm and also reduces its weight, making it possible to increase the high-frequency reproduction limit frequency without reducing efficiency.

In this example, a hole is made in the diaphragm of the treble speaker, and a microphone is installed in this part, but it is not necessary to make a hole in the diaphragm. A similar effect can be obtained by fixing a tweeter's acoustic equalizer or grill close to the diaphragm near the axis of the diaphragm.

Effects of the Invention Since the speaker device of the present invention can detect the vibration characteristics of the speaker without contacting the diaphragm, MFB can be applied without reducing the efficiency of the speaker and without affecting the frequency characteristics, making it possible to detect the vibration characteristics of the speaker without contacting the diaphragm. It is possible to control high-pitched speakers, which was previously impossible, and also to reduce distortion and control frequency characteristics, which has the effect of being extremely useful.

[Brief explanation of the drawing]

Fig. 1 is a system block diagram of a conventional MFB, Fig. (5) 2 is a sectional view of a speaker according to an embodiment of the present invention, Fig. 3 is a system block diagram of the MFH, and Fig. 4 shows sound before and after the MFB. It is a pressure frequency characteristic diagram. 1...Power amplifier, 2'...Treble speaker, 4.
...Feedback circuit, 5...Microphone, 6...Diaphragm (6) 2nd = 4 Figure 3 No. 4 Port

Claims (3)

[Claims] (1) A speaker device including a treble speaker and a feedback microphone provided in the center of a diaphragm of the treble speaker to detect sound reproduced by the speaker and control the speaker. (2) The speaker device according to claim 1, wherein the feedback microphone is disposed in a hole provided in the center of the diaphragm of the high-pitched speaker. (3) The speaker device according to claim (1), wherein the feedback microphone is arranged at the front of the diaphragm of the high-pitched speaker without providing a hole in the diaphragm.