JP2821611B2 - Handset - Google Patents

Description

The present invention relates to a receiver provided in a telephone such as a public telephone or a car telephone.

B. Summary of the Invention The present invention relates to a receiver provided in a telephone such as a public telephone or a car telephone, in which a speaker unit and a microphone unit are provided near the earpiece, and the microphone unit converts the acoustic signal near the earpiece into an electric signal. Converted,
The external noise is reduced by negatively feeding back the electric signal obtained by the microphone unit to the input terminal of the amplifier circuit that amplifies the input reception signal supplied as an electric signal to the speaker unit via a feedback circuit. The S / N of the sound output from the speaker unit is increased so that the voice of the other party can be clearly heard.

C. Prior Art In general, a telephone handset generally includes a receiver provided with a microphone unit for converting an input reception signal supplied as an electric signal into an acoustic output, and a transmitter which converts a transmission sound into an electric signal. It consists of a transmitter with a microphone unit. Conventionally, telephones used in high-noise situations such as public telephones and car telephones on the street use handsets similar to ordinary telephones, and telephones that can change the sound output level of a handset are also provided. ing.

D Problems to be Solved by the Invention By the way, in a telephone used in a high noise level situation such as a public telephone in a street or a car telephone, since the surrounding noise reaches the ear of use, it is difficult to hear the voice of the other party. It has been extremely difficult to make it possible to clearly hear the voice of the other party only by increasing the sound output level of the receiver.

Accordingly, the present invention has been made in view of the above-described problems of the conventional telephone, and has as its object to realize, for example, a telephone that can be used even in an environment with a high noise level, thereby reducing external noise reaching a user's ear. Accordingly, the present invention provides a receiver having a novel configuration in which the S / N ratio of a received sound is increased and the voice of the other party can be clearly heard.

E Means for Solving the Problems In order to achieve the above object, a handset according to the present invention includes a speaker unit having an H transfer function for converting an input reception signal supplied as an electric signal into an audio signal and outputting the audio signal. The transfer function for amplifying the input reception signal supplied to the speaker unit is A, the microphone function for converting the acoustic signal in the vicinity of the earpiece into an electric signal is M, and the microphone unit is obtained for the transfer function. A transfer function for negatively feeding back a signal to an input terminal of the amplifier circuit; and a feedback circuit having β, wherein the amplifier circuit, the speaker unit,
Let the transfer functions of the microphone unit and feedback circuit be | A
HMβ | >> 1 and the speaker unit and the microphone unit are provided near the earpiece.

F Function In the handset according to the present invention, an acoustic signal including external noise in the vicinity of the earpiece provided with the speaker unit is converted into an electric signal by the microphone unit, and the input received signal supplied to the speaker unit as an electric signal is amplified. The electric signal obtained by the microphone unit is negatively fed back to the input terminal of the amplification circuit through the feedback circuit.

By setting each transfer function of the amplifier circuit, speaker unit, microphone unit and feedback circuit in the range of | AHMβ | >> 1, the acoustic signal near the earpiece is
The signal level of external noise is reduced to 1 / AHMβ.

G Embodiment Hereinafter, an embodiment of the handset according to the present invention will be described in detail with reference to the drawings.

The embodiment shown in FIG. 1 applies the present invention to a telephone handset (4) provided with a mouthpiece (2) and a mouthpiece (3) at both ends of a grip (1) as shown in FIG. The speaker unit (14) and the microphone unit (16) constituting the receiver (10) according to the present invention are provided in the earpiece (2) on the upper end side of the grip (1).

The receiver (10) is provided with a speaker unit (14) and a microphone unit (16) in the earpiece (2) portion of the handset (4) as shown in FIG. A signal synthesizer (12) provided on the input side of an amplifier circuit (13) for amplifying an input reception signal S provided as an electric signal supplied to a signal input terminal (11) and supplying the amplified signal to the speaker unit (14); The sound signal near the earpiece (2) is converted into an electric signal by the microphone unit (16) and supplied to the signal synthesizer (12) via a feedback circuit (17). )
, The output of the feedback circuit (17), that is, the feedback signal, is combined with the input reception signal S and supplied to the amplifier circuit (13) to perform the negative feedback control of the amplifier circuit (13).

The transfer functions indicating the characteristics of the amplifier circuit (13), the speaker unit (14), the microphone unit (16), and the feedback circuit (17) in the frequency domain are the transfer function A of the amplifier circuit (13), The transfer function H of the speaker unit (14), the transfer function M of the microphone unit (16), and the transfer function β of the feedback circuit (17) are | AHMβ | >>
It is set within a range that satisfies the condition (1).

As shown in the equivalent block diagram of FIG. 3, the receiver (10) is a signal adder equivalent to an acoustic output signal from the speaker unit (14) in an acoustic space near the earpiece (2). In (15), the noise signal N from the outside is added, and the combined output of the signal adder (15) is converted into an electric signal in the microphone unit (16), and the electric signal is converted through the feedback circuit (17). The signal is supplied to a signal synthesizer (12).

A signal output terminal (19) corresponding to an entrance of a user's ear (20) of the receiver (10) has a signal level S of an input reception signal applied to the signal input terminal (11), and a signal input terminal (18). ), The signal level N of the external noise signal given to the signal adder (15) The sound output of the sound pressure level P, that is, the input received signal S is given a conversion characteristic of 1 / Mβ to correct the frequency characteristic and distortion, and the signal level N of the external noise is 1 / AHMβ A clear received voice with a large S / N ratio is obtained.

Therefore, in the handset (10), even under an environment with a high ambient noise level, the external noise input to the user's ear (20) is reduced, and the S / S of the sound output by the speaker unit (14) is reduced. By increasing the N ratio, the voice of the other party can be clearly heard.

In order to adjust the volume of the sound output obtained at the signal output terminal (19), a volume adjuster may be provided in front of the signal input terminal (11), that is, at the sound source side.

H Effect of the Invention In the handset according to the present invention, an acoustic signal including external noise in the vicinity of a mouthpiece provided with a speaker unit is converted into an electric signal by a microphone unit, and an input reception signal supplied to the speaker unit as an electric signal. An electric signal obtained by the microphone unit is negatively fed back to an input terminal of an amplifier circuit for amplifying the signal through a feedback circuit, and each transfer function of the amplifier circuit, speaker unit, microphone unit, and feedback circuit is represented by | AHMβ | >> By setting the range to 1, the signal level of external noise near the earpiece is reduced to 1 / AHMβ.

Therefore, according to the present invention, the external noise input to the user's ear (20) is reduced, and the S / N ratio of the sound output by the speaker unit is increased even in an environment with a high ambient noise level. In addition, it is possible to provide a receiver that can clearly hear the voice of the other party.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the principle configuration of a handset according to the present invention, FIG. 2 is an external perspective view of a telephone handset to which the present invention is applied, and FIG. 3 is an equivalent block diagram of the above handset. (2)… Earpiece (4)… Handset (10)… Handset (11)… Signal input terminal (12)… Signal synthesizer (13)… Amplifier circuit (14)… Headphone unit ( 17) Feedback circuit (16) Microphone unit

Continuation of the front page (56) References JP-A-60-220689 (JP, A) JP-A-62-2798 (JP, A) JP-A-64-7798 (JP, A) , U) Actual opening Sho 61-70486 (JP, U) Special table Sho 63-503186 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04R 3/00 H04M 1/00

Claims (1)

(57) [Claims] 1. A speaker unit having an H transfer function for converting an input reception signal supplied as an electric signal into an acoustic signal and outputting the sound signal, and an A transfer function for amplifying the input reception signal supplied to the speaker unit. Circuit, a microphone unit having a transfer function of converting an acoustic signal in the vicinity of the earpiece into an electric signal, and a feedback circuit having a transfer function of negatively feeding back a signal obtained by the microphone unit to an input terminal of the amplifier circuit. Wherein the transfer functions of the amplifier circuit, speaker unit, microphone unit and feedback circuit are set within the range of | AHMβ | >> 1 and the speaker unit and microphone unit are provided near the earpiece. Handset.