JP2782840B2 - Mobile phone - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a small-sized mobile phone that can be carried with one hand, and more particularly to a mobile phone that allows hands-free communication. This type of general mobile phone is also called a pocket phone, and is mainly connected via a car phone line.
It is used to make a call between a mobile phone inside the car and a phone outside the car while the car is running or stopped.

(Prior Art) FIGS. 3 and 4 show the appearance and configuration of a conventional mobile phone, respectively.

The mobile phone shown in FIG. 3 has a transmitter 1, a receiver 2, an antenna 3, an operation unit 4, a battery, and the like integrated together. As an example, the overall size is about 180 × 120 × 42 ( mm),
The weight is about 900g. This portable telephone holds a handset, puts the transmitter 1 in the mouth and the receiver 2 in the ear, and performs a so-called handset call.

The operation will be described with reference to FIG. 4. A speaker's voice signal is input to the transmitter 1, and the radio wave is transmitted from the antenna 3 via the amplifier 5, the control unit 6, the wireless device 7, and the transmission / reception splitter 8. The data is transmitted to a base station (not shown) and input to the telephone of the other party who is a general telephone subscriber.

On the other hand, the audio signal from the other party is input to the antenna 3,
The signal is output from the receiver 2 at the level adjusted by the volume control variable resistor 9 via the transmission / reception splitter 8, the wireless device 7, and the control unit 6 via the reverse route, and the telephone conversation is performed.

The side tone circuit 10 is used for a digital portable telephone, and is different from the side-tone prevention circuit of a general telephone, and is composed of a simple resistance circuit connected between the transmitter 1 and the receiver 2.
This is intended to intentionally leak a side tone, that is, a voice signal component of the speaker, which wraps around the receiver 2, and eliminates a sense of discomfort given to the speaker when this component is completely absent.

(Problems to be Solved by the Invention) However, conventional mobile phones are large in size, and have various irregularities in the outer shape as shown in FIG.
The shape was not refined in terms of design, and the storage was insufficient. In addition, there is a problem in that only a conventional handset call in which a telephone must be held by hand at all times during a call and a transmitter and a receiver must be put on a mouth and an ear, respectively.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes at least a microphone for transmitting, a speaker for receiving, an antenna for transmitting and receiving signals, and a wireless transmitting and receiving circuit. In a mobile phone, a sidetone circuit connected between a microphone and a speaker, an echo canceller connected in parallel to this sidetone circuit, and during a handset call, the sidetone circuit is turned on and the echo canceler is turned off. And switching means for turning off the side tone circuit and turning on the echo canceller during a hands-free call.

(Operation) According to the present invention having the above-described configuration, when performing a handset call, the sidetone circuit is switched on by the switching means and the echo canceller is turned off, so that only the sidetone circuit is connected, and the handset call can be performed. It is performed without trouble. Further, when performing a hands-free call, the sidetone circuit is switched off and the echo canceller is turned on by the switching means, so that a hands-free call with excellent voice quality without echo, howling, etc. can be performed.

(Embodiment) FIGS. 1 and 2 show the appearance and configuration of an embodiment of a mobile phone according to the present invention, respectively.

As shown in FIG. 1, the telephone is accommodated in a case 12 having a structure that can be folded by a hinge 11, and the case 12 is compactly folded when being carried, and is opened and used during a call. A handset call is made with the upper handset 13 and the lower handset 14 in FIG. 1 fully open, ie, about 180 °, and placed on a flat surface for hands-free operation. When making a call, the receiver 13 and the transmitter 14 should be
Open to make an angle of about 0 °.

Switching between a handset call and a hands-free call is performed by a handset call / hands-free call switch 15. Also, instead of the receiving speaker 16, a hands-free call can be made using an earphone 17 connected to the output side of the variable resistor 9 (FIG. 2).

Reference numeral 18 denotes a display unit for displaying information such as the time, the call duration, and the telephone number of the other party.

In FIG. 2, a voice signal R from the other party, which is a general telephone subscriber, is output from a receiving speaker 16 via a control unit 6 and a variable resistor 9. This audio signal R is received by the receiving speaker 1
6. In the external space of the telephone set between the transmission microphones 19, an acoustic echo R 'is input to the transmission microphone 19 as an acoustic echo R'.
, Becomes an amplified acoustic echo R ″, is superimposed on the voice signal of the speaker, and is transmitted to the other party again via the control unit 6, the wireless device 7, and the antenna 3. This acoustic echo R ″ is transmitted to the other party. Since one's own voice is returned, not only does this hinder the call, but when the loss of the call line is small, the loop gain increases and howling occurs.

An echo canceller 20 is introduced to cancel the amplified acoustic echo R ″. The echo canceller 20 receives the voice signal R as an input signal and estimates the transfer characteristic of the acoustic echo path on the left side of the echo canceller 20 in FIG. Then, a pseudo echo output from the echo canceller 20 is output from the adder 21. Is subtracted from the acoustic echo R ″ to eliminate the acoustic echo R ″. The residual signal e is fed back to the echo canceller 20, and the echo canceller 20 performs adaptive estimation control of the echo path so that the residual signal e is minimized.

Handset call / hands-free call switch 15
Is switched to the handset call side, the echo canceller 20 is off, And the side tone circuit 10 connected between the receiving speaker 16 and the transmitting microphone 19 leaks the transmission signal to the receiving speaker 16 side. When the changeover switch 15 is switched to the hands-free call side, the echo canceller 20 is turned on and the pseudo echo And the hands-free call is performed without any trouble, while the side tone circuit 10 is disconnected.

(Effects of the Invention) As described above, according to the present invention, it can be folded into a small and compact form, is convenient to carry and has excellent storage properties, and is stable and hands-free with very little howling due to the use of an echo canceller. A hands-free mobile phone capable of making a call is obtained.

Furthermore, when it is not desired to hear the sound from the receiving speaker in another hands-free call, the sound can be heard with an earphone.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of an embodiment of a mobile phone according to the present invention, FIG. 2 is a block diagram showing the configuration of the mobile phone of FIG. 1, and FIG. 3 is a perspective view showing the appearance of a conventional mobile phone. FIG. 4 is a block diagram showing the configuration of the mobile phone shown in FIG. 1 ... transmitter, 2 ... receiver, 3 ... antenna, 4 ... operator, 5 ... amplifier, 6 ... controller, 7 ... radio equipment, 8 ... transmitter / receiver splitter, 9 ... … Variable resistor, 10… Side tone circuit, 11… Hinge, 12… Case, 13… Handset, 14… Handset, 15… Handset call / hands-free call switch, 16… ... Receiver speaker, 17 ... Earphone, 18 ... Display unit, 19 ... Transmit microphone, 20 ... Echo canceller, 21 ... Adder, R ... Sound signal, R ', R "... Acoustic echo ,

Continuation of the front page (56) References JP-A-63-187845 (JP, A) JP-A-63-187844 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04M 1 / 00 H04M 1/60-1/62

Claims (1)

(57) [Claims] A microphone for transmitting, a speaker for receiving,
In a mobile phone having at least an antenna for transmitting and receiving transmission and reception signals and a radio transmission and reception circuit, a sidetone circuit connected between the microphone and the speaker, an echo canceller connected in parallel to the sidetone circuit, and a handset call Sometimes, the side tone circuit is turned on, and the echo canceller is turned off, and at the time of a hands-free call, the side tone circuit is turned off, and switching means for switching the echo canceller on is provided. Mobile phone.