JPS645799B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a microphone device in which the S/N ratio is less degraded due to ambient noise or inherent noise of the microphone itself.

Conventional configuration and its problems In general, microphone devices have their own specific directivity, and a comparison of the directivity pattern of a unidirectional microphone and the directivity pattern of a secondary sound pressure gradient microphone is made. As is clear from
Secondary sound pressure gradient microphones are better at removing ambient noise than unidirectional microphones, but the higher the sound pressure gradient, the greater the inherent noise. is inferior to a unidirectional microphone. As described above, the removal of ambient noise caused by the microphone device's own directivity pattern and the reduction of inherent noise are contradictory, and it has not been possible to achieve both of these requirements by reducing the overall noise.

OBJECTS OF THE INVENTION An object of the present invention is to provide a microphone device in which the total noise of ambient noise and unique noise is small, and the deterioration of S/N due to these noises can be reduced.

Structure of the Invention The microphone device of the present invention compares each output of a low-order sound pressure gradient type microphone unit and a high-order sound pressure gradient type microphone unit arranged facing the same direction, and outputs each of the above units according to the comparison result. It is configured to select the output from.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows an embodiment of the present invention.
In the figure, reference numeral 11 denotes a unidirectional microphone unit, which has a directivity pattern shown in FIG. 2a. Reference numeral 12 denotes a secondary sound pressure gradient type microphone unit, which has a directivity pattern shown in FIG. 2b. The unidirectional microphone unit 11 and the secondary sound pressure gradient type microphone unit 12 are arranged with their directivity axes facing in the same direction. 13 is a comparison circuit between the output of the unidirectional microphone unit 11 and the output of the secondary sound pressure gradient type microphone unit 12; 14 is a switch that is switched according to the output state of the comparison circuit 13; The outputs of the directional microphone unit 11 and the secondary sound pressure gradient type microphone unit 12 are switched according to the output state of the comparator circuit 13 and outputted to an output terminal 15.

In such a configuration, the output of the unidirectional microphone unit 11 having the directivity pattern shown in FIG. 2a and the secondary sound pressure gradient type microphone unit 1 having the directivity pattern shown in FIG.
The two outputs are compared in a comparison circuit 13, and if the difference is small, the switch 14 is switched to the unidirectional microphone unit 11, and if the difference is large, the switch 14 is switched to the unidirectional microphone unit 11.
can be switched to the side. According to this system, when ambient noise is large, the output of the unidirectional microphone unit 11, which has a blunt directivity, becomes larger than the output of the secondary sound pressure gradient type microphone unit 12, which has a sharp directivity. is switched to the secondary sound pressure gradient type microphone unit 12 side, and ambient noise is removed. The secondary sound pressure gradient type microphone unit 12 has a larger inherent noise than the unidirectional microphone unit 11, but when the surrounding noise is large, the contribution of this inherent noise is small, and the overall S/N can be improved. I can do it. On the other hand, on the contrary, the ambient noise is reduced and the unidirectional microphone units 11 and 2
When the output difference of the second sound pressure gradient type microphone unit 12 becomes smaller, the switch 14 is switched to the side of the unidirectional microphone unit 11, which has a smaller inherent noise. Therefore, in this case, since the contribution of inherent noise is large, the unidirectional microphone unit 1
Switching to the 1 side can improve the overall S/N.

FIG. 3 shows another embodiment of the present invention. In FIG. 3, 21 is a unidirectional microphone unit, 22 is a secondary sound pressure gradient type microphone unit, and both of these units 21 and 22 are They are arranged so that their directional axes point in the same direction. 23-1, 23-2...... are band pass filters to which the respective outputs of the unidirectional microphone unit 21 and the secondary sound pressure gradient type microphone unit 22 are applied, and 24-1, 24-2...... are band pass filters. The above band pass filters 23-1, 23-2...
The above unidirectional microphone unit 2
Comparison circuits 25-1 and 25-2 for comparing each output of the first and second-order sound pressure gradient type microphone units 22;
. . . is a switch that is switched according to each output state of the comparison circuits 24-1, 24-2, and the band pass filters 23-1, 23-2 .
The above unidirectional microphone unit 2
The respective outputs of the first and second order sound pressure gradient type microphone units 22 are switched according to the respective output states of the comparison circuits 24-1 and 24-2. 26
is the unidirectional microphone unit 21 selected by the switches 25-1, 25-2...
An adder 27 is an output terminal of the adder 26 and an adder 27 which synthesizes each output of the secondary sound pressure gradient type microphone unit 22. Here, the comparison circuit 24-
1, 24-2...... is the above band pass filter 2
In comparing the unidirectional microphone unit 21 and the secondary sound pressure gradient type microphone unit 22 through the microphones 3-1, 23-2......, if the difference is small, the switches 25-1, 25-2 ……
... to the unidirectional microphone unit 21 side, and if the difference is large, switch 25-
1, 25-2...... are switched to the secondary sound pressure gradient type microphone unit 22 side.

In such a configuration, the output of the unidirectional microphone unit 21 and the output of the secondary sound pressure gradient type microphone unit 22 are band-divided by bandpass filters 23-1, 23-2, etc., and the respective frequencies are divided. Comparison circuits 24-1, 24 in the band
-2…… and switch 25-1, 25-2……
Both the microphone units 21 and 22 are selected so as to have the best S/N, and the adder 26
are synthesized and taken out to the output terminal 27. Therefore, since directivity including frequency components can be switched, the S/N ratio can be further improved.

In the above embodiment, the combination of a unidirectional microphone unit, that is, a primary sound pressure gradient type microphone unit and a secondary sound pressure gradient type microphone unit was explained, but a combination of a low-order sound pressure gradient type and a high-order sound pressure gradient type microphone unit was explained. It goes without saying that the present invention is not limited to this and can be implemented as long as each unit is combined with a slope type.

Effects of the Invention As detailed above, according to the present invention, each output of a low-order sound pressure gradient type microphone unit and a high-order sound pressure gradient type microphone unit arranged facing the same direction is compared by a comparison circuit. However, since the switch provided on the output side of both units is changed based on the comparison result of the comparison circuit,
If the output difference between the two units is small in the comparison result of the comparison circuit, the low-order sound pressure gradient type microphone unit is selected, and if the output difference is small, the high-order sound pressure gradient type microphone unit is selected. As a result, it is possible to control the total noise of ambient noise and the inherent noise of the microphone itself to always be minimized, and to reduce the deterioration of S/N due to these noises and achieve high S/N. It has the advantage of being able to make sounds.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the microphone device of the present invention, and FIGS. 2a and 2b are directivity pattern diagrams of the microphone unit used in the device.
FIG. 3 is a block diagram showing another embodiment of the microphone device of the present invention. 11...unidirectional microphone unit, 1
2... Secondary sound pressure gradient type microphone unit, 1
3... Comparison circuit, 14... Switch, 15... Output terminal, 21... Unidirectional microphone unit, 22... Quadratic gradient type microphone unit,
23-1, 23-2...Band pass filter, 2
4-1, 24-2... Comparison circuit, 25-1, 25
-2...Switch, 26...Adder, 27...Output terminal.

Claims (1)

[Claims] 1. Each output of a low-order sound pressure gradient type microphone unit and a high-order sound pressure gradient type microphone unit arranged in the same direction is compared in a comparison circuit, and the comparison result in the comparison circuit is When the output difference between the two units is small, the output of the low-order sound pressure gradient type microphone unit is taken out, and when the output difference is large, the output of the above-mentioned high-order sound pressure gradient type microphone unit is taken out. A microphone device configured to be switched by a switch provided on the side. 2. A comparison circuit and a switch that is switched according to the comparison result of this comparison circuit are used to divide the frequency bands provided on each output side of the low-order sound pressure gradient type microphone unit and the high-order sound pressure gradient type microphone unit. A patent claim characterized in that the signal is provided for each bandpass filter, and is frequency-divided by the bandpass filter, and the signals selected by the comparison circuit and the switch are combined and extracted by an adder. The microphone device according to item 1.