JPS5994993A - Microphone device - Google Patents

Abstract

PURPOSE:To use the microphone device on a desk by arranging a pair of sec- ondary sound pressure inclination type bidirectional microphones to plane vertical to the directivity of an unifirectional characteristic microphone to make both directivity axis orthogonal and to add or subtract the output of each microphone to obtain laterally flat directivity. CONSTITUTION:The pair of the secondary sound pressure inclination type directivity microphone units 12, 13 consisting of a unidirectional microphone unit 11 and non-directional microphone units 21-24, 31-34, are provided. The units 12, 13 are arranged in the plane where the directivity axis of the unit 11 is vertical to make the directivity axes of the units 12, 13 orthogonal with each other. The outputs of the units 21-24, and 31-34 of the units 12, 13 are synthesized by synthesis circuits 25, 35, and the outputs of the circuits 25, 35 are added by an adder 14. The output of the adder 14 is substrated from the output of the unit 11 by a substractor 15 to obtain a laterally flat directivity at an output terminal 16.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a microphone device with excellent directional characteristics, typified by a secondary sound pressure gradient type high directional microphone.

Conventional configuration and its problems In general, secondary sound pressure gradient type height 2 7 with excellent directional characteristics
．． - As shown in Figure 1, directional microphones are unidirectional microphone devices (1+2t') that are placed in front of and behind the sound source, and unidirectional microphones that are placed behind the sound source. The phase shift circuit 3 adjusts the phase shift of the output of the microphone unit 2, and the subtracter 4 converts the output of the unidirectional microphone unit 1 placed in front of the sound source into the above-mentioned phase-adjusted unidirectional. The configuration was such that the output signal of the microphone unit 2 was reduced. With this process,
From the unidirectional microphone unit 1.2 having the directivity 6 of (1+COSθ) shown in FIG. 2 to the (
A secondary sound pressure gradient type highly directional microphone having a directivity of 6 of 1+cos aogo can be obtained. Here, θ is the angle between the directional axis and the sound source. However, in the conventional secondary sound pressure gradient type high directional microphone described above, the unidirectional microphone unit is arranged in front and behind the sound source. Since it has a long shape from front to back, if it is installed on a desk with a small depth, it will cause inconvenience such as not being able to place a speech manuscript when using it on a desk.
The object of the present invention is to provide a secondary sound pressure gradient type high directional microphone with excellent directivity. (1+ come) cozy
An object of the present invention is to provide a microphone device that achieves directivity with a horizontally flat shape instead of a conventional long shape from front to back, and which is easy to install on a desk or the like.

Structure of the Invention The microphone device of the present invention includes a unidirectional microphone unit and a pair of unidirectional microphone units arranged such that their directional axes are orthogonal to each other in a plane perpendicular to the directional axis of the unidirectional microphone unit. (1) has a secondary sound pressure gradient type bidirectional microphone unit (1), adds each output of the pair of secondary sound pressure gradient type bidirectional microphone units, and calculates the result from the output of the unidirectional microphone unit. The configuration is such that the above-mentioned addition output is reduced.

DESCRIPTION OF EMBODIMENTS FIG. 4 shows an embodiment of the present invention. In FIG. 4, 11 is a unidirectional microphone element), 12.1
3 are arranged in a plane perpendicular to the directional axis 2 of the unidirectional microphone unit 11 so that their directional axes x and y are perpendicular to each other. The second secondary sound pressure gradient type bidirectional microphone unit 7), 14 is the first one. Second secondary sound pressure gradient type bidirectional microphone unit) 12.1
15 is a subtracter that subtracts the output of the adder 14 from the output of the unidirectional microphone unit 11; 16 is an output terminal of the subtracter 15; The directional microphone unit 11 is the fifth
It has a directivity of (1+aos0) shown in Figure a.

Here, the first secondary sound pressure gradient type bidirectional microphone unit 12 is an omnidirectional microphone unit disposed on the X axis in a plane perpendicular to the directivity axis 2 of the unidirectional microphone unit 11. 21, 22, 23.2
4 and these omnidirectional microphone units 21, 22.
23. A synthesis circuit 26 for synthesizing each of the outputs of 24 is configured in a similar manner.The output of the synthesis circuit 26 receives a bidirectional signal of cos2θ about the X-axis as shown in FIG. 7. On the other hand, the second secondary sound pressure gradient type microphone unit 13 is an omnidirectional microphone arranged on the y-axis perpendicular to the X-axis in a plane perpendicular to the directional axis 2 of the unidirectional microphone unit 110. 31, 32, 33, 34 and a synthesis circuit 36 that synthesizes the respective outputs of these omnidirectional microphone units 31.32, 33.34, and the output of the synthesis circuit 36 is as shown in FIG. cow about the y-axis shown in C.
A signal having bidirectionality of 2θ is extracted.

In such a configuration, the above-mentioned first and second secondary sound pressure gradient type bidirectional microphone units 12, 1
When each output of 3 is added in an adder 14, the adder 1
As shown in FIG. 5d, the output of No. 4 is omnidirectional in the x-y plane and has a donut-shaped directivity with no sensitivity in two axes. Therefore, by subtracting the output of the above-mentioned donut-shaped directivity from the output of the unidirectional microphone 11 having the directivity of (1+oogθ), the output terminal 16 is It is possible to obtain a signal with the directivity shown in Figure 6e, which eliminates the sensitivity in the 90° direction, that is, the x-y plane direction, without changing the sensitivity in the two-axis directions.This directivity is the first As mentioned in the conventional example in the figure (1+c
osθ) COSθ, which is the same as the directivity of a high-directivity microphone with a high secondary sound pressure gradient.

Effects of the Invention As detailed above, according to the present invention, a pair of secondary sound pressure gradient shapes are arranged such that their directivity axes are orthogonal to each other in a plane perpendicular to the directivity axis of the unidirectional microphone unit. Bidirectional microphone units are arranged, each output of the pair of secondary sound pressure gradient type bidirectional microphone units is added, and the added output is subtracted from the output of the unidirectional microphone unit. Therefore, it has the advantage that the same sharp directivity as the conventional one can be obtained with the flat shape in which the microphone element is arranged on the x-y plane perpendicular to the directivity axis of the unidirectional microphone unit.

Therefore, it has the advantage of being very convenient when used by taking advantage of its flat shape, for example when used on a desk.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional microphone device. Figures 2 and 3 are diagrams showing the directivity characteristics of signals in each part of the device, Figure 4 is a block diagram showing an embodiment of the microphone device of the present invention, and Figures 5a-e are diagrams showing each part of the device. FIG. 2 is a diagram showing the directional characteristics of a signal. 11...Unidirectional microphone unit, 1
2.13...Second-order sound pressure gradient bidirectional microphone unit 21, 22, 23, 24, 31, 32゜3
3.34°°°...Negligible directional microphone unit 2
5.36...Synthesis circuit, 14...Adder, 16...Subtractor. Name of agent: Patent attorney Toshio Nakao and one other person. Figure 1 Figure 4 Meeting α b c dLe

Claims (1)

[Claims] a unidirectional microphone unit; and a pair of unidirectional microphone units arranged such that their directional axes are perpendicular to each other in a plane perpendicular to the directional axis of the unidirectional microphone unit.
Next sound pressure gradient type bidirectional microphone unit and this 1
A microphone device comprising: adding means for adding the respective outputs of a pair of secondary sound pressure gradient bidirectional microphone units; and subtracting means for subtracting the output of the adding means from the output of the unidirectional microphone unit.