JPH0846679A - Cordless telephone set - Google Patents

Abstract

PURPOSE:To realize the handfree function and to attain speech in a sense close to a usual receiver speech by providing a level control section decreasing a sound volume sounded from a speaker with a detection signal of a level detection section. CONSTITUTION:A level detection section 5 of a master set 1A detects a transmission signal level outputted from a cordless transmission reception section 3. When a level of a transmission signal from a slave set 1B exceeds a prescribed signal level, the level detection section 5 provides an output of a control signal to a level control section 6. The level control section 6 receiving the control signal decreases the level of the transmission signal fed to a power amplifier 9 via a variable resistor 7 corresponding thereto. In the interlocking operation between the level detection section 5 and the level control section 6, when howling takes place between a speaker 10 and a microphone 13 through the close distance between the master set 1A and the slave set 1B depending on the convenience of use by the user, the sound volume of the sound sounded from the speaker 10 is decreased to prevent in advance the production of a large sound volume from the speaker 10 due to howling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone having a hands-free function.

[0002]

2. Description of the Related Art Cordless telephones equipped with a so-called hands-free function have the following types of communication methods. That is,

Switching system (half-duplex system) This is a system in which the levels of the transmitting side and the receiving side are compared, and only the one with a higher level is given a priority call. Since this method is a one-way call in principle, you cannot speak like a normal telephone, and you can just listen when the other party is talking, and speak when you are finished talking. There is

Simultaneous call system (full-duplex system) This is a system in which an echo canceling circuit is used to make a simultaneous call between a transmitting side and a receiving side. This system is ideal because it can be spoken like a normal telephone, but the quality of the call is greatly affected by the performance of the so-called echo cancellation circuit, and the call becomes extremely bad depending on the degree of cancellation. Also, optimizing the echo cancellation circuit for each line for each call poses many practical problems (becomes expensive), so the setting must be made for a typical line, and the call quality on average Will tend to worsen.

Now, as a method of realizing the hands-free function of a cordless telephone, there is a method of arranging a microphone and a speaker in a main body housing. However, since the base unit is relatively small, the level of the sound transmitted from the speaker to the microphone is higher than the level of the sound transmitted by the speaker. There is a problem that howling may occur between the microphone and the speaker, which may hinder the communication. Also,
As another method of realizing the hands-free function of a cordless telephone, a slave unit is provided with a microphone for inputting a transmission sound and a receiver for outputting a transmission / reception sound, and a speaker that emits the transmission / reception sound on a stand of the slave unit. Is arranged (for example, Japanese Patent Laid-Open No. 4-243354). However, since the positional relationship between the microphone of the child device and the speaker of the stand is close, howling may occur between the microphone and the speaker.

[0006]

As described above, the simultaneous call system capable of speaking like an ordinary phone is required as the call system of the cordless telephone. However, when this system is adopted, it depends on the performance of the echo cancellation circuit. It is typical because the call quality is greatly affected, and depending on the degree of cancellation, the call becomes very bad, and optimizing the echo cancel circuit for each line is practically problematic (expensive). There is a problem that the call quality tends to deteriorate on the average because the setting must be made for a different line.

Further, as a method of realizing the hands-free function of the cordless telephone, there is a method of arranging a microphone and a speaker in a main body housing, but there is a fear that howling may occur and a telephone call may be disturbed. There was a problem that there is.

An object of the present invention is to provide a cordless telephone which can realize a hands-free function without depending on a switching system or a simultaneous communication system, and can make a call with a feeling similar to a normal handset communication. is there.

[0009]

In order to solve the above-mentioned problems, the present invention provides a cordless telephone having the following structure. In the cordless telephone 1 for making a wireless call between the master unit 1A and the slave unit 1B,
B includes a microphone 13 for inputting a transmission / reception sound and a receiver 14 for outputting a transmission / reception sound, and the base unit 1A detects a speaker 10 for emitting the transmission / reception sound and a transmission sound at a predetermined level or higher. Level detecting section 5 and this level detecting section 5
And a level control unit 6 for reducing the sound volume of the speaker 10 according to the detection signal of the cordless telephone.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cordless telephone according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a cordless telephone of the present invention.

The cordless telephone 1 of the present invention comprises a base unit 1A and a handset 1B. The base unit 1A includes a speech network 2, a cordless transmitter / receiver 3, an antenna 4, a level detector 5, a level controller 6, a volume (VR) 7, a (normally open) switch 8, a power amplifier 9, and a speaker 10. The cordless transceiver 1 is the cordless handset 1B.
1, an antenna 12, a microphone 13, and a receiver 14.

The cordless telephone 1 of the present invention can realize a hands-free function without depending on the switching system or the simultaneous communication system described above, and moreover, it is possible to talk with a feeling similar to a normal handset communication. explain. That is, it is sufficient if the rate at which the sound produced by the receiving section is picked up by the transmitting section is small, as in the case of handset communication. However, when the earpiece (speaker) and the transmitter (microphone) are arranged in the same housing, the ratio of the sound picked up by the transmitter (pronounced by the receiver) is much higher than that of the receiver. Therefore, the switching method or the simultaneous call method described above is required. However, even if such a system is not adopted, it is sufficient if the distance between the receiving section (speaker) and the transmitting section (microphone) can be set sufficiently. Accordingly, the speaker 10 is provided in the base unit 1A of the cordless telephone 1, and the microphone 13 is arranged in the handset 1B. In addition, base unit 1
The reason why the level detection unit 5 and the level control unit 6 arranged in A are necessary is that there is no problem when the distance between the receiving unit (speaker) and the transmitting unit (microphone) is sufficiently large as described above. However, the cordless telephone 1 has a cordless handset 1B as a base unit 1A.
Since it is possible to approach the speaker 10 of No. 1, a means for suppressing howling at that time is required. The level detection unit 5 and the level control unit 6 operate as means for suppressing this howling.

Next, the operation of the cordless telephone 1 will be described in the order of (1) receiving call and (2) sending call.

(1) Reception The reception signal transmitted via the telephone line 1 via the public line or the dedicated line is transmitted to the cordless transmission / reception section 3 and one end of the switch 8 via the speech network section 2 constituting the master unit 1A. Supplied. The cordless transmission / reception unit 3 performs a transmission process on the reception signal, and then wirelessly transmits the reception signal via the antenna 4. The cordless transmitter / receiver 11 of the child device 1B receives and processes the received signal from the parent device 1A which is wirelessly transmitted via the antenna 12, and then the receiver 14
Send to. On the other hand, the reception signal supplied to one end of the switch 8 via the speech network unit 2 of the master unit 1A has the switch 8 when the hands-free function is selected.
Is switched from off to on, the level is adjusted by the volume 7 through the switch 8, the desired amount is amplified by the power amplifier 9, and then the sound is emitted from the speaker 10. Thus, when the hands-free function is selected, the speaker 1 of the base unit 1A
0 sounds the receiving signal and the receiver 1 of the handset 1B
4 can listen to the received signal from the base unit 1A (when the hands-free function is not selected, the receiver 1 of the handset unit 1B)
It goes without saying that only the receiving signal can be heard at No. 4).

(2) Speaking The voice of the speaker is picked up by the microphone 13 of the handset 1B,
The collected transmission signal is subjected to transmission processing by the cordless transmission / reception unit 11 and then wirelessly transmitted via the antenna 4. The cordless transmission / reception unit 3 of the base unit 1A receives the transmission signal wirelessly transmitted from the extension unit 1B, and then outputs the transmission signal to the level detection unit 5 and the speech network 2, respectively.
The speech network 2 transmits this transmission signal to the public line or the dedicated line via the telephone line l, and when the hands-free function is selected, the switch 8 is changed from the off state to the on state. After being amplified by the power amplifier 9 by a desired amount, sound is emitted from the speaker 10. Thus, when selecting the hands-free function, the base unit 1
The speaker 10 of A outputs the transmission signal from the handset 1B (when the handsfree function is not selected, the speaker 1 of the base 1A)
It goes without saying that 0 does not sound the transmission signal).

By the way, the level detection unit 5 of the base unit 1A detects the level of the transmission signal output from the cordless transmission / reception unit 3. The level detection unit 5 outputs a control signal to the level control unit 6 when the level of the transmission signal from the handset 1B exceeds a predetermined signal level. When the level control unit 6 is supplied with this control signal, the level of the transmission signal supplied to the power amplifier 9 via the volume 7 in response to the control signal is reduced (muted or reduced). , Shut off). Such interlocking of the level detection unit 5 and the level control unit 6 makes the main unit 1A and the sub unit 1B approach each other and the sound emitted from the speaker 10 of the main unit 1A is output by the sub unit 1B according to the usability of the user. When the howl is picked up (picked up) by the microphone 13 and the howling is caused between the speaker 10 and the microphone 13, the speaker 10
This is performed in order to prevent the generation of a loud sound from the speaker 10 due to howling by reducing the sound volume of the sound being emitted. This interlocking is to prevent the loud sound from being output from the speaker 10 of the master unit 1A when an excessive sound (impact sound or the like) is input to the microphone 13 of the slave unit 1B.

[0017]

Since the cordless telephone of the present invention is provided with the microphone and the receiver in the slave unit (the microphone is not provided in the master unit), the hands-free function can be realized without depending on the switching system or the simultaneous communication system. Since it is possible, it is possible to make a call with a feeling similar to that of a normal handset call. Since the cordless telephone of the present invention is provided with the level detecting section for detecting the transmission sound of the predetermined level or higher on the base unit side and the level control section for reducing the sound volume of the speaker by the detection signal of the level detecting section, It is possible to prevent howling between the microphone of the child device and the speaker of the parent device caused by the approach between the parent devices.

[Brief description of drawings]

FIG. 1 is a block diagram of a cordless telephone of the present invention.

[Explanation of symbols]

 1 cordless telephone 1A base unit 1B handset 5 level detection unit 6 level control unit 10 speaker 13 microphone 14 receiver

Claims (1)

[Claims] 1. A cordless telephone for wireless communication between a master unit and a slave unit, wherein the slave unit includes a microphone for inputting a transmission sound and a receiver for outputting a transmission / reception sound. A speaker for emitting a transmitted / received sound, a level detection unit for detecting a transmitted sound of a predetermined level or higher, and a level control unit for reducing the sound volume of the speaker by a detection signal of the level detection unit. Cordless phone.