JPH02250596A - Electroacoustic transducer - Google Patents

Abstract

PURPOSE:To simplify a circuit configuration by making a single electroacoustic transducer to simultaneously function as both a speaker and a microphone. CONSTITUTION:An electroacoustic transducer 11 provided on one side of a bridge circuit 15 is made to function as the speaker, input signals VIN applied to signal input terminals 16A and 16B as electric inputs are converted into acoustic signals SOUT by means of the electroacoustic transducer 11, outputted, simultaneously the electroacoustic transducer 11 is made to function as the microphone, acoustic signals SIN applied as the acoustic inputs are converted into electric signals VOUT by the electroacoustic transducer 11, and outputted from a signal output terminal. That is, in an electroacoustic transducing device, a single electroacoustic transducer 11 simultaneously functions as both the speaker and the microphone. Thus the configuration can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION 8. Field of Industrial Application The present invention relates to an electroacoustic transducer having a function of converting an electrical signal into an acoustic signal and a function of converting an acoustic signal into an electrical signal, such as an active noise reduction device. It is commonly used for headphone devices and headphone microphone devices for recording pinosils.

B. Summary of the Invention The present invention provides a bridge circuit that satisfies a balance condition in which an electroacoustic transducer having a reversible electroacoustic conversion function is connected to one side, and by providing a signal input terminal pair and seven signal output terminal pairs. The electric signal inputted between the pair of signal output terminals is converted into an acoustic signal by the electroacoustic converter and outputted, and the electric signal converted from the acoustic signal by the electric acoustic W converter is transferred to the pair of signal output terminals. This realizes an electroacoustic transducer that can be obtained in between.

C. Conventional technology In general, speakers, headphones, etc., which are electroacoustic transducers that convert electrical signals into acoustic signals, and microphones, which are electroacoustic transducers that convert acoustic signals into electrical signals, are provided as separate devices. For example, individual speakers and microphones are often placed close to each other, such as in so-called active noise reduction headphone devices or high-noise recording headphone/microphone devices that require both speakers and microphones.

The active noise reduction headphone device converts an electrical signal into an acoustic signal and outputs the sound signal near the headphone unit.The microphone unit converts an acoustic signal into an electrical signal, and returns the signal in an opposite phase using a negative feedback loop. It is designed to reduce noise near the unit, for example, Japanese Patent Application Laid-Open No. 60-220698 and Japanese Patent Laid-Open No. 60-220698.
It is disclosed in Japanese Patent No. 2-2798 and the like.

The active noise reduction headphone device described above has a basic configuration shown in FIG.
A microphone unit (3) is provided near the headphone unit (2) to be attached to the signal source (
A signal synthesizer (6) is provided on the input side of the amplification circuit (7) which amplifies the input electric signal given to the signal input terminal (5) from the signal input terminal (5) from the headphone unit (2). 2) The microphone unit (3) converts a nearby acoustic signal into an electrical signal, supplies it to the signal synthesizer (6) via the feedback circuit (8), and inputs it to the signal synthesizer (6). The above feedback circuit (8) to the electrical signal
The output, that is, the feedback signal is synthesized and the above amplifier circuit (7)
By supplying the signal to the amplifier circuit (7), negative and negative feedback control of the amplifier circuit (7) is performed.

Like this active noise reduction headphone device, an acoustic signal obtained by adding the acoustic output signal from the headphone unit (2) and the external noise signal N is obtained near the auditory canal entrance of the listener's ear (1). The acoustic signal obtained by adding the noise signal from the outside is converted into an electrical signal by the microphone unit (3), and the acoustic signal is sent to the feedback circuit (8).
) to the input side of the amplifier circuit (2), the noise level of the acoustic signal input to the listener's ear (1) can be lowered.

In addition, a pinaural recording headphone microphone device is a device in which a pinaural recording microphone and a monitor speaker are placed in close proximity to each other in order to monitor the recording state when performing pinaural recording on a tape recorder or the like. It is disclosed in 60-10156 and the like.

Furthermore, telephones, intercoms, etc. are equipped with separate microphones for transmitting and speakers for receiving calls in order to realize a two-way simultaneous conversation function that allows transmitting and receiving calls at the same time.

Dynamic speakers and capacitor microphone units are known as electroacoustic transducers that can operate reversibly in principle, and are used in simplex two-way communication devices such as simple intercoms and transceivers. For example, a so-called breathtalk system is adopted in which a dynamic speaker is switched between a speaker and a microphone.

D Problems to be Solved by the Invention By the way, as mentioned above, the active noise reduction headphone device, the Pinosil recording headphone microphone device, the intercom having the function of two-way simultaneous calling, etc. require the function of a speaker and the function of a microphone. However, since individual speakers and microphones were provided separately, there was a problem in that the placement of the speakers and howling countermeasures had to be taken into consideration.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional art. The present invention provides an electroacoustic transducer with a novel configuration that can convert and output the following.

E! II! Means for Solving the Problems In order to achieve the above-mentioned object, the electroacoustic transducer according to the present invention uses a bridge circuit that satisfies a balance condition in which an electroacoustic transducer having a reversible electroacoustic transducing function is connected on one side. , is characterized by being provided with a pair of signal input terminals and a pair of signal output terminals.

F action In the electroacoustic transducer according to the present invention, an input electrical signal given to a signal input terminal provided in a bridge circuit in which an electroacoustic transducer having a reversible electroacoustic transducing function is connected to one side is transferred to the electroacoustic transducer. At the same time, an electrical signal obtained by converting the acoustic signal input to the electroacoustic transducer is obtained at a signal output terminal provided in the Brifuji circuit.

G. Example Hereinafter, an example of an electroacoustic transducer according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit configuration diagram showing the basic configuration of an electroacoustic transducer (10) according to the present invention.

This electroacoustic transducer (10) includes an electroacoustic transducer (1
A pair of signal input terminals (16A) and (16B) and a signal output terminal (1) are connected to the bridge circuit (15) with 1) connected to the - side.
7^) + (17B) A pair is provided.

The bridge circuit (15) includes the electroacoustic transducer (1
1) and the impedance 2 of the electroacoustic transducer (11)
, a circuit element (12) having an impedance Zl (Z, -Zl) characteristic equivalent to the characteristic, and a mutually equal resistance value R,
, R2 (R,=R1) (13).

It consists of (14), Z, ·R, -Zl ·R.

The equilibrium condition is satisfied.

As the electroacoustic transducer (11), one having a reversible electroacoustic conversion function, such as a dynamic speaker or a condenser microphone, is used.

In the electroacoustic transducer (10) having such a configuration, when input electric signals v, H are applied from the signal source (19) between the signal input terminals (16^) and (16B), the bridge circuit (15 ) A signal current corresponding to the input electrical signal VIN flows through the electroacoustic transducer (11) provided on the - side of It is converted into a signal s out and output. Since the bridge circuit (15) has a configuration that satisfies the equilibrium condition, the signal input terminal (16A)
.

The input electric signal VIN applied between the pair (16B) does not cause a potential difference between the signal output terminal (17^) and the pair (17B). However, when the electric acoustic transducer (11 ), when the acoustic signal SIN is applied to the electroacoustic converter (11), the acoustic signal S4 is converted into an electric signal, thereby adjusting the balance of the Brifuji circuit (15) according to the acoustic input signal SIN. The above signal output terminals (17A) and (17B
) Output electric signal ■ corresponding to the acoustic input signal SIN between the pairs. II? is obtained.

In this way, in the electroacoustic transducer (lO) according to the present invention, the electroacoustic transducer (11) provided on the negative side of the bridge circuit (15) functions as a speaker, and the signal input terminal (16A) , (16B) as an electrical input is converted into an acoustic signal S by the electroacoustic transducer (11). At the same time, the electroacoustic transducer (11) is made to function as a micropon, and the acoustic signal SIN given as an acoustic input is converted into an electrical signal V by the electroacoustic transducer (11). Convert to one signal output terminal (17A),
(17B) can be output.

FIG. 2 is a circuit configuration diagram showing the main part configuration of an embodiment in which the present invention is applied to an active type noise reduction headphone device.

This active type noise reduction headphone device amplifies an input electrical signal and uses the electroacoustic transducer (20) according to the present invention.
an amplifier circuit (31) that supplies the pair of signal input terminals (26A) and (26B), a signal synthesizer (32) provided on the input side of the amplifier circuit (31), and the electroacoustic transducer (20 ) signal output terminals (27A), (27B
) a feedback circuit (33) that supplies an output electric signal obtained between the pair as a feedback signal to the signal combiner (32) to perform negative drain control of the amplifier circuit (33).

The electroacoustic transducer (20) includes a dynamic electroacoustic transducer (21) and an impedance Z equivalent to the impedance Z I+ characteristic of the electroacoustic transducer (21).
A circuit element (2
2) and mutually equal resistance values RIl, RI! (R31-
A bridge circuit (2
5), the above signal input terminals (26A) and (26B)
A pair of signal output terminals (27A) and a pair of signal output terminals (27B) are provided.

In this embodiment, an impedance Z1□ (Z
, Y-L+) A dynamic electroacoustic transducer (22A) having the same structure as the electroacoustic transducer (21) is housed and sealed in a small container (22B). .

Further, the bridge circuit (25) includes the circuit element (2
2) and each of the resistors (23) and (24) are built into the signal source main body, and the electroacoustic transducer (21) provided at the tip of the external cord (28) is provided in the signal source main body. By inserting the plug (29B) into the jack (29A), it is connected to the - side.

In the active noise reduction headphone device having such a configuration, the electroacoustic transducer (20) simultaneously functions as a speaker and a microphone with - electroacoustic transducers (21), so feedback control for noise reduction is possible. can be performed stably, and the configuration can be simplified. Moreover,
By incorporating the circuit element (22) and each of the resistors (23) and (24) constituting the bridge circuit (25) into the tape recorder main body (20), an external connection cord to the signal source main body is provided. (29) can also be used as an output signal line and an input signal line.

Here, an electroacoustic transducer used as a headphone device, - for boat fishing, has a low resonant frequency f0 of 100 to 200 Hz.
It has an impedance characteristic as shown in Fig. 3, and if a circuit element equivalent to the above impedance characteristic is constructed using ordinary passive elements such as R, L, and C, a large size glue and C are required. , although it is not possible to obtain a practical one, as in this example, a similar electroacoustic transducer (
By using 21) and (22A), the balance of the bridge circuit (25) can be made extremely high, and moreover, the bridge circuit (25) can be made smaller.

Further, as a circuit element having impedance characteristics equivalent to the electroacoustic transducer constituting the electroacoustic transducer according to the present invention, it is possible to combine an active element such as an operational amplifier with passive elements such as R, L, and C. FD RN (Fre
quency DependentNegative
Re5istance) circuit elements may also be used.

In addition, although the present invention was applied to an active type noise reduction headphone device in the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment, and can be applied to a two-way communication system such as an intercom or a pinaural recording device. It can be applied to systems that require both speaker and microphone functions, such as headphone microphone devices.

H Effects of the Invention In the electroacoustic transducer according to the present invention, an input electric signal given to a signal input terminal provided in a bridge circuit in which an electroacoustic transducer having a reversible electroacoustic conversion function is connected to one side is converted into the electroacoustic transducer. The transducer converts it into an acoustic signal and outputs it, and the electrical signal obtained by converting the acoustic signal input to the electroacoustic transducer is obtained at the signal output terminal provided in the bridge circuit. A converter can function as a speaker and a microphone at the same time. Further, in the electroacoustic transducer according to the present invention, an electroacoustic transducer connected to one side of the bridge circuit and a circuit element in which an electroacoustic transducer equivalent to the electroacoustic transducer is housed and sealed in a container are included in the bridge circuit. By providing it on the other side, the balance of the bridge circuit can be easily and reliably maintained, and a stable electroacoustic conversion operation can be performed. Furthermore, in the electroacoustic transducer according to the present invention, an FDRN element having impedance characteristics equivalent to that of the electroacoustic transducer connected to one side of the bridge circuit is provided on the other side of the bridge circuit.
The balance of the bridge circuit described above can be easily and reliably obtained using a small circuit element.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing the basic configuration of an electroacoustic transducer according to the present invention, and FIG. 2 is a circuit configuration diagram showing the main part configuration of an active type noise reduction headphone device to which the present invention is applied.
FIG. 3 is a characteristic diagram showing a single impedance characteristic of the electroacoustic transducer used in the headphone device. FIG. 4 is a circuit configuration diagram showing the basic configuration of an active type noise reduction headphone device. (10) , (20) ・・・・・・・・・・・・
・・・・・・(11) , (21) ・・・・・・
・・・・・・・・・(15) , (25) ・・
・・・・・・・・・・・・・・・(16A) , (1
6B) , (26^)+ (26B) ... (1
7A), (17B), (27A), (27
B)... Electroacoustic transducer Electroacoustic transducer bridge circuit Signal input terminal Signal output terminal Frequency → Fig. 4

Claims (3)

[Claims] (1) A bridge circuit that satisfies the equilibrium condition in which an electroacoustic transducer with a reversible electroacoustic conversion function is connected on one side,
An electroacoustic transducer comprising a pair of signal input terminals and a pair of signal output terminals. (2) A circuit element in which an electroacoustic transducer equivalent to the electroacoustic transducer is housed in a container and sealed is provided on the other side of the bridge circuit. Sound conversion device. (3) The electroacoustic transducer according to claim (1), wherein an FDRN element having impedance characteristics equivalent to that of the electroacoustic transducer is provided on the other side of the bridge circuit.