JPS59149494A - Microphone device - Google Patents

Abstract

PURPOSE:To improve low-frequency directivity by arranging plural unidirectional microphone units and four nondirectional microphone units, the mixing their outputs together. CONSTITUTION:Plural unidirectional microphone units 21-27 are arranged on a straight line vertical to their axes of directivity or arcuately close to the straight line. The 1st microphone sums up and outputs the outputs of the unidirectional microphone units. Further, four nondirectional microphone units are arranged on the same array line with the unidirectional microphone units 21-27 and the 2nd microphone outputs the difference between the sum of the outputs of two inside units and the sum of the outputs of the two outside units. The outputs of the 1st and the 2nd microphones are made composite by the composite circuit consisting of a filter 36 and a subtracter 29 to be outputted. Thus, the low-frequency directivity of the microphone is made sharp.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Use The present invention relates to a microphone device for use in amplification or recording that is resistant to howling and difficult to pick up ambient noise.

Conventional configuration and its problems A conventional example is shown in FIG. 1, and will be explained first.

This is done by arranging unidirectional microphones 1 to 7 with directivity as shown in 8 on a straight line with their directivity axes in the o0 direction in the figure. 7 is added by an adder 9 and output.

FIG. 2 shows the characteristics of the above conventional example. In the figure, 11 indicates the output in the 0° direction of FIG. 1, 12 indicates the output in the 900° direction, and 13 indicates the output in the 180° direction, and 14.15 indicates the directivity patterns in the low and high frequencies.

As a result, conventional devices have very sharp directivity in the high range, but are unidirectional in the low range, resulting in a lack of directivity in the low range, which has been a major problem.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a microphone device that improves the conventional low-frequency directivity and has sharp directivity over the entire band.

Structure of the Invention The present invention arranges a plurality of unidirectional microphones on a straight line perpendicular to the directivity axis or in an arc shape close to the straight line, and adds the outputs of these unidirectional microphones. A first microphone that outputs a signal, and four omnidirectional microphone units are arranged on the same array line as the unidirectional microphone, and the output sum of the inner two and the output sum of the outer two a second microphone that outputs the difference between the first and second microphones; This microphone device includes a circuit that synthesizes the output of a second microphone.

DESCRIPTION OF AN ACTUAL SIZE EXAMPLE An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

In FIG. 3, the unidirectional microphone units 21 to 27 and the adder 28 have exactly the same configuration as the conventional example shown in FIG. 1, and serve as the first microphone.

31-341/j: Unidirectional microphone Unisoto 2
This is an omnidirectional microphone unit arranged on the same straight line as 1 to 27, and these and the adder/subtractor 35 constitute a second microphone.

This first. The output of the second microphone is filtered by filter 3
6 and a subtracter 29, and output.

Fig. 4 shows the characteristics of the embodiment shown in Fig. 3, where 41 indicates the output in the 0° direction, 42 indicates the output in the 9'Oo direction, 43 indicates the output in the 180° direction, and 44.45 indicates the low frequency output. and high-frequency directional pattern.

It can be seen from FIG. 4 that the microphone according to the present invention has greatly improved low frequency directivity.

This principle will be explained in detail below.

Now, assuming that the sound source is at the θ angle position in FIG. The low frequency output of the second microphone can be expressed by the following equation.

Output of the first microphone E1=F'(B (10 cosθ)) Output of the second microphone E2=F''(o
(S1n2θ) Here, F'(f) is a function indicating the sensitivity and frequency dependence of the first microphone, and F/(, is a function indicating the sensitivity and frequency dependence of the second microphone.

Now, by inserting a filter having the characteristic F'(f)/F''(f) into E2, the following output E2' can be obtained.

Subtracting this F'2 from El yields the following output.

Eout2F(q (10cosθ−5in2(1)=
F' (f) (1 + cos θ) cos θ this E Out
Directivity: , (1+cos)cosθ is the secondary sound IJ
, E-gradient type high directivity, and even sharper directivity than single directivity, that is, the directivity pattern 44 in FIG. 4 can be obtained.

In the embodiment of FIG. 3, the filter 36 or F(f)/F'(B
The Kaede subtractor 29 adjusts E
, -E≦.

In the above embodiment, the microphones were arranged in a straight line, but even if they were arranged in an arc with one point as the center as shown in Fig. 5, the low-frequency directivity would be; I can get leprosy.

As described in detail, the present invention makes it possible to sharpen the low-frequency directivity without impairing the appearance of the conventional example, and it is possible to realize a microphone with extremely excellent directivity.

By using this microphone, it is possible to amplify the sound with less howling, and it is also possible to collect sound with less ambient noise.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional example, Fig. 2 is a frequency characteristic diagram, Fig. 3 is a block diagram showing an embodiment of the present invention, Fig. 4 is a frequency characteristic diagram, and Fig. 5 is a diagram showing the same frequency characteristics. FIG. 7 is a diagram showing an example of the arrangement of microphones in another embodiment. 21-27...unidirectional microphone unit, 31-34...omnidirectional microphone unit, 28...adder, 29...subtraction device, 35...-adder/subtractor, 36...filter.

Claims (1)

[Claims] A plurality of unidirectional microphones are arranged on a straight line perpendicular to the directivity axis of the unidirectional microphones or in an arc shape close to the straight line, and the outputs of these unidirectional microphones are summed and output. microphone and four omnidirectional microphone units are arranged on the same array line as the unidirectional microphone, and the difference between the output sum of the inner two microphones and the output sum of the outer two microphones is output. 2 microphone, and the first microphone. A microphone device configured with a circuit that synthesizes the output of a second microphone.