JP2000138745A - Telephone system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a telephone system capable of full duplex communication without feedbacks. SOLUTION: In this telephone system, a handset uses a 1st speakerphone 20, which converts an audio input into an electric transmission signal and simultaneously converts an electric received signal indicating audio data into an audio output and is provided with an amplification compressor 24 which communicates with the speakerphone 20. The amplifying and compressing device 24 receives a composite signal consisting of the transmission signal and the received signal, amplifies the transmission signal, also compresses the received signal and generates an output signal, in which the transmission signal is at least ten times as large as the received signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone device for carrying out transmission and reception while holding all handsets by hand.

[0002]

2. Description of the Related Art Conventionally, all handsets of telephone equipment have a structure in which handsets are transmitted and received. That is, when making a telephone call, the user talks with the handset facing the ear and the mouth by hand, but there are various inconveniences. For example, if you talk for a long time,
Hand with handset is easy to get tired. Also, in places such as stations and department stores where noise is loud, the received voice may be difficult to hear due to the influence of external noise.

[0003] In a telephone device, it is good to use full-duplex communication for a speakerphone, but it is difficult to apply "full-duplex communication" to a speakerphone due to problems of voice and electric feedback. When the voice returns from the speaker to the microphone, voice feedback occurs. The same applies to the electric feedback, except that the electric feedback is based on an audio input (a signal transmitted to the remote controller) and an audio output (a signal received from the remote controller). The transmitting circuit and the receiving circuit are not separated from each other, and the gain of the formed loop is 1
If so, electrical feedback occurs. In order to completely eliminate feedback, the total loop gain, including those due to speech and electricity, must be less than one.

[0004] The speaker horns for hands-free and group communication are mainly in a half-duplex arrangement. In such an arrangement, the following mutual switching (1) and (2) is performed using a high-speed switch circuit. (1) Output audio through a speaker. (2) Listen with a separate microphone. Without such switching, there is an audio feedback path from the loudspeaker to the microphone. Since the switch circuit can prevent the speaker and the microphone from operating at the same time, the audio output from the speaker does not induce an electrical signal to the microphone. Although troublesome noise can be canceled by switching circuits, there are various disadvantages. That is, the user cannot transmit and listen at the same time. The switch circuit compares the intensities of the signals emitted from both, and transmits only the strong signal among them.

Since full-duplex communication requires a complete closed loop circuit for both calling and receiving at the same time,
Its total loop gain must be less than or equal to one. As a method of reducing the loop gain to 1 or less, there is a method of detecting and canceling feedback using a digital signal process. A speakerphone according to this method may be referred to as a digital or full-duplex speaker. This type of device consists of separate speakers and microphones, and analog circuits corresponding to digital arithmetic circuits. The analog circuit has an appropriate filter for determining a difference value of a signal gain between a transmission path and a reception path. This difference value is generated by the audio output of the received signal reaching the transmitting part of the loop via the microphone. Depending on the result of detecting the feedback, the device reduces the loop gain to less than one with either electronically controlled attenuator on either side of the loop.

[0006] The attenuator can reduce the annoying noise due to the feedback and reduce the gain of the audio output so that the user cannot hear it, so that the potential function of the device can be exhibited. However, sometimes the attenuator may reduce the gain of the received signal so that the user does not even hear the other party. Also, the cost of a digital circuit arrangement is several times higher than that of a half-duplex speakerphone arrangement.

US Pat. No. 4,002,860 discloses a method for solving a kind of voice feedback problem. Although the communication circuit described in this patent uses a speakerphone that functions both as audio feedback and a microphone, the communication circuit according to this patent cannot efficiently cancel the electrical feedback. Although this communication circuit uses a hybrid speakerphone to separate a transmission signal and a reception signal, it can actually separate only 15 dB. The amount of separation depends primarily on the ability of the circuit to blend the impedance of the speakerphone and the telephone line. As long as the circuit does not have the ability to separate the transmitted and received signals, significant feedback is inevitable.

Another disadvantage of the US Pat. No. 4,002,860 patent is that the circuit carries the load through a speakerphone. The speakerphone load interferes with the transmission signal generated in the speakerphone due to voice input, thus impairing the function of the circuit. In a typical microphone, the signal due to the user's sound is only about 10 mV, which is very small. Any load on the speakerphone will cause the energy of the signal to be lost. To compensate for such energy loss, the transmit signal processing circuit may amplify small audio signals. However, if any received signal feedback is fed back to the amplifier of the transmitting circuit, the aforementioned feedback problem is significant.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a telephone device capable of full-duplex communication without feedback.

[0010]

According to one aspect of the present invention, there is provided a telephone apparatus comprising a telephone body and a handset connected to the telephone body, wherein the handset is an audio system. A first speakerphone for converting an input into an electric transmission signal and simultaneously converting an electric reception signal indicating audio data into an audio output is used, and a compression / amplifier for communicating with the first speakerphone is provided. Receiving a composite signal including the transmission signal and the reception signal, and amplifying the transmission signal and compressing the reception signal to generate an output signal in which the transmission signal is at least ten times larger than the reception signal. I do.

According to a second aspect of the present invention, there is provided a matching impedance element for matching the impedance of the first speakerphone and receiving the reception signal, a compressor connected to the matching impedance element,
And a differential amplifier connected to the compressor / amplifier and the compressor.

According to a third aspect of the present invention, the matching impedance element is a second speakerphone that converts an audio input into a second electric transmission signal and converts this electric reception signal into an audio output. The amplifier is part of a second compression / amplifier and is connected to the second speakerphone, and the differential amplifier is connected to the second compression / amplifier.

According to a fourth aspect of the present invention, in order to transmit a received signal to the first speakerphone without applying a load to the first speakerphone, the first speakerphone is connected to a linear amplifier. Features.

According to a fifth aspect of the present invention, the linear amplifier uses an operational amplifier having a non-inverting input and an inverting input, the non-inverting input receiving the reception signal, and the inverting input being the first input. It is connected to a speakerphone, and the linear amplifier transmits a reception signal to the speakerphone by the reverse input without applying a load to the speakerphone.

The invention according to claim 6 is characterized in that the speakerphone is driven by the received signal and a two-way transistor for amplifying a signal transmitted by the speakerphone is provided.

According to a seventh aspect of the present invention, the transistor has a base, a collector, and an emitter, the base receiving the reception signal, and the speakerphone having a matching impedance connected to the emitter and the collector. It is connected to the element.

The invention according to claim 8 is an inverter connected to the collector, an amplifier connected to the output of the speakerphone between the speakerphone and the compression / amplifier, and compressing the received signal. A compressor connected to the inverter, and a differential amplifier connected to the compressor / amplifier and the compressor, and the differential amplifier includes the composite signal from the compressor / amplifier and the compressor. And receiving the received signal from the receiver and almost canceling the received signal.

The invention according to claim 9 is characterized in that it has an output stage for receiving the output signal of the compression / amplifier, amplifying the transmission signal and compressing the reception signal, The invention according to claim 10 is characterized in that the speakerphone is a speaker and an earphone, and the invention according to claim 11 is characterized in that the speakerphone is a speaker and a microphone. In the above invention, the telephone body is a telephone device main body.
The telephone body is a telephone main unit, and the invention according to claim 14 is characterized in that the telephone body is a telephone slave unit.
The telephone body is attached to an arm.

[0019]

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a telephone body according to an embodiment of the present invention, FIG. 2 is a perspective view showing a handset according to Embodiment 1 of the present invention, and FIG. 3 is a perspective view showing a use mode of the telephone device. . As shown in FIGS. 1 and 2, the telephone device includes a portable telephone body 1 and a handset 2 connected to the telephone body 1. In particular, the telephone body 1 is attached to the wrist, and the handset 2 converts the audio input into an electric transmission signal and simultaneously converts the electric reception signal indicating the audio data into an audio output (speaker / earphone) 20 (FIG. 9) and, as shown in FIG. 9, an amplifier 22 connected to the speakerphone 20 and a compression / amplifier 24 connected to the amplifier 22 are provided, and the speakerphone 20, the amplifier 22 and the compression / amplifier 24 Form a dual audio communication circuit.

The amplifier 22 receives an electric input signal (received signal Rx) indicating an audio input and transmits the signal to the speakerphone 20. The speakerphone 20 converts the received signal into an audio output. The speakerphone 20 converts an audio input such as a user's voice into an electric transmission signal (transmission signal Tx). Therefore, if the speakerphone 20 has a function of a microphone for converting an audio input into an electric transmission signal, it also has a function of a speaker (earphone) for converting an electric signal from an external source into an audio output.
In particular, since the functions of the speaker and the microphone are realized by a single speakerphone, there is no audio feedback path. Therefore, there is no need to use an electronically controlled attenuator to reduce the effects of audio feedback.

Since the speakerphone 20 simultaneously receives the Rx signal and generates the Tx signal, a combined transmission / reception signal (Tx + Rx) is obtained at the output end of the speakerphone 20. The amplifier 22 transmits the composite signal to the compression / amplifier 24. The compression / amplifier 24 outputs Rx
Compress the signal and amplify the Tx signal.

It is desirable that the compression / amplifier 24 uses a logarithmic circuit. This type of circuit amplifies the Tx signal with a logarithmic function and compresses the Rx signal. For example, speakerphone 2
At 0, the generated Tx signal is an Rx signal (about 300 mV)
Is very small (about 3 mV). Compression / amplifier 2
Reference numeral 4 has a function of compressing a signal within a certain voltage range, but amplifies a signal within another voltage range. The purpose is to transmit the Tx signal and almost cancel the Rx signal so that no feedback occurs.
To accomplish this, the compression and amplifier 24 compresses beyond a certain threshold voltage level, while amplifying it so as not to exceed a certain threshold level. As described above, the compression / amplifier 24 simultaneously amplifies and amplifies a different signal by simultaneously compressing or amplifying different signals, and
The x signal can be reduced. Therefore, the difference between the transmission signal and the reception signal can be reduced.

[0023] The very good point of Embodiment 1 is that
The amplifier 22 is to avoid loading of the speakerphone 20. The amplifier 22 drives the speakerphone 20 so as to minimize the loss of the reception signal and the transmission signal. To obtain the best performance, the load applied to the received signal speakerphone 20 must be minimized. Any load on the speakerphone 20 will cause a portion of the transmitted signal to be lost. Since the transmitted signal is usually much smaller than the received signal, loss of a portion of the transmitted signal can degrade performance. Also, when generating the transmit signal, the receive signal in speakerphone 20 must not be lost. In order to prevent interference between the transmission signal and the reception signal, a method of providing an impedance (shunt) between the speakerphone 20 and the reception signal source has been proposed. However, such a shunt causes a partial loss of the reception signal. It is not preferable to divide the current into the speakerphone 20. In the present embodiment, the amplifier 22 is connected to the speakerphone 20 in order to prevent a load from being applied to the speakerphone 20 and to divide the load. Therefore, this amplifier 2
2 transmits the Tx signal with almost negligible loss,
The Rx signal is applied to the speakerphone 20 with almost negligible loss.

The telephone apparatus shown in FIG. 1 may use the audio communication circuit shown in FIG. In this circuit, Tx
And the Rx signal level are small (or both are at substantially the same level). This circuit has two input stages of matching, each of which has speakers and earphones 40 and 42 and amplifiers 44 and 46, respectively. Either of the two input stages operates as described above for FIG. However, the speaker / earphones 40 and 42 are connected to each other with different polarities. Thus, the transmission signals of the two input stages have a phase difference of 180 °. Since the impedances of the two input stages are balanced, both received signals have substantially the same magnitude and phase, and the transmitted signals have the same magnitude, but there is a 180 ° difference in phase.

The circuit has a differential amplifier 48.
The differential amplifier 48 receives a composite transmission / reception signal as input, amplifies the transmission signal Tx, and cancels the reception signal Rx. Normally, the output of differential amplifier 48 is proportional to the two input signals. Since the two received signals Rx and Rx have substantially the same phase, they are canceled each other. However, both received signals R
The degree to which x and Rx cancel each other depends on the matching state of the two input stages. Theoretically, the impedances of the two input stages are perfectly matched, but in practice it is difficult to achieve a perfect balance due to variations in each facility. Therefore, when the two input stages are matched, the received signals Rx and Rx are output from the differential amplifier 4.
8 is almost canceled at the output end, but not completely canceled. Further, since the impedance of the received signal source changes well, there is a possibility that a phase difference may occur between the impedances of the input stages.

However, since the received signal is canceled by using the differential amplifier 48, the speaker / earphone 40 or 42 is not necessarily used in all input stages. The speaker / earphone 40 or 42 may be replaced with a matching impedance. The matching impedance here is an induct or an RLC circuit having the same impedance function as the speaker / earphone 40 or 42. When a matching impedance device is used instead of the speaker / earphone 40 or 42, the transmission signal Tx is not generated at the input stage without the speaker / earphone 40 or 42, but another differential amplifier is arranged to connect to the reception signal source. It has a function similar to that of the side. The differential amplifier 48 substantially cancels the received signals on the various sides, and also outputs the speaker / earphone 40 or 42.
Amplify the transmission signal Tx on the side having In all input stages, a speaker / earphone 40 or 42
Is not used, but it is advantageous to use the same type of speaker / earphone in all input stages. One is to give the user a feeling of truth and a sense of the field. For example,
Audio output can be heard through the two speakers / earphones 40 and 42 for both the left and right ears. Since the differential amplifier 48 enhances the input signals with reverse polarity, the transmitted signal from the circuit is large. Also, when the same type of speaker / earphone is used on various sides, matching of impedance and phase is easily achieved.

In general, the circuit shown in FIG. 10 has an effect similar to that of the circuit shown in FIG. That is, the received signal can be reduced and the transmitted signal can be amplified. However, if the amount of separation between the Tx signal and the Rx signal is too large, a method of matching the compression / amplifier and the differential amplifier is used to effectively cancel the Rx signal in the Tx-Rx composite signal. There is a need. The Tx signal generated in the speaker and earphone 40 or 42 by the audio input is much smaller than the Rx signal from the telephone line. The compression / amplifier can reduce the amount of separation between the Tx signal and the Rx signal,
The differential amplifier effectively cancels the Rx signal in the same mode as the Tx signal.

This telephone device may use the audio communication circuit shown in FIG. The circuit shown in FIG. 11 summarizes the characteristics of the circuits shown in FIGS. 9 and 10. That is,
This circuit uses not only the differential amplifier 72 but also the compression / amplifiers 68 and 70 to simultaneously compress the received signal and amplify the transmitted signal. The differential amplifier arrangement of this circuit has an input stage with two matching impedances. Each of the two input stages has a speaker / earphone 60 and 62 and an amplifier 64 and 66, respectively. Each side of the differential amplifier arrangement has compression and amplifiers 68, 70 for simultaneously compressing the received signal and amplifying the transmitted signal. The differential amplifier 72 receives the combined transmission / reception signal (Tx + Rx) from each side, cancels the reception signal Rx on the opposite side, and enhances the transmission signal Tx.

The circuit shown in FIG. 11 can effectively cancel the reception signal and amplify the transmission signal by integrating the differential amplifier arrangement and the compression / amplifier. It has higher performance functions than circuits. This circuit preferably has a speaker and earphone on each side. Also, a speaker / earphone 60 is provided on one side.
Alternatively, 62 may be replaced with a suitable impedance element. In this case, a compressor is used instead of the compression / amplifier 68 or 70 because there is no received signal on the side having impedance.

The circuits shown in FIG. 9 to FIG.
It has an audio process circuit that can receive a composite signal based on the x signal amount, amplify the Tx signal amount and compress the Rx signal amount, and connect to a speaker / earphone. For an audio process circuit, the ability to substantially cancel Rx and generate a Tx signal that is larger than the Rx signal depends on the levels of the Tx and Rx signals in the loudspeaker / earphone and the specific arrangement of the audio circuit.

In FIG. 9, the audio process circuit has a compression / amplifier 24. If the Tx signal is much smaller than the Rx signal, this compression amplifier 24 is very effective in reducing the difference between the Tx and Rx signals. However, in a normal case, the Tx signal from the speaker / earphone is very small. Therefore, the Tx signal cannot be made larger than the Rx signal to cancel the Rx signal only by the compression / amplifier.

In FIG. 10, the audio process circuit has a differential amplifier 48. If the two input sides of the differential amplifier 48 are well matched and the amount of separation between the Tx and Rx signals is very small, then the differential amplifier can effectively cancel the Rx signal corresponding to the Tx signal. it can. However, when the levels of the Tx signal and the Rx signal do not sufficiently match, the differential amplifier alone does not provide an excellent effect.

In FIG. 11, the audio process circuit is a circuit in which compression / amplifiers 68 and 70 and a differential amplifier 72 are generalized. First, the compression / amplifiers 68 and 70 are Tx and R
The audio process circuit can effectively cancel the Rx signal corresponding to the Tx signal since the difference between the x signals is reduced and the differential amplifier 72 substantially cancels the common mode Rx signal.

The detailed contents of the audio process circuits shown in FIGS. 9, 10 and 11 are shown in the detailed configuration diagram of the full-duplex audio communication circuit of FIG. The circuit shown in FIG. 12 amplifies a transmission signal at the same time as the circuit shown in FIG. 11 and reduces the reception signal from an external audio source. . Speaker / earphones 100 and 102, amplifiers 104 and 106, and compression / amplifiers 108 and 110 are provided on all sides of the differential amplifier arrangement.

The output terminals 112 and 114 of the compression / amplifiers provided on both sides of the differential amplifier
6 is connected. The output of differential amplifier 116 is connected to output stage 118. The output stage 118 amplifies the transmission signal, compresses the reception signal, and adjusts the output voltage level to a normal level. The output stage 118 outputs the final transmitted signal 120 and at least 30
An almost negligible received signal having a low dB can be generated. This circuit can achieve a full-duplex function with very little feedback by simultaneously compressing the received signal and amplifying the transmitted signal.

The input received signal 122 enters the circuit by a pass band equalizer 124. During this special arrangement,
The pass band equalizer 124 uses a normal bipolar pass band equalizer. The function of this pass band equalizer equalizes the audio output of the speaker / earphone 100, 102. At higher frequencies, the frequency response of the received signal is particularly weak. In order to equalize the frequency of the received signal, the pass band equalizer includes a leakage circuit that offsets and balances the frequency response.

Output 1 of pass band equalizer 124
Reference numeral 26 denotes a differential amplifier arrangement. Amplifiers 104 and 106 on both sides.
Supplied to FIG. 7 shows a method in which when a received signal is applied to a speaker / earphone by an amplifier, the speaker / earphone does not load or shunt.
In the first embodiment, the amplifier 104 includes the resistor R1 (130)
The resistance R1 (130)
Is connected between the antiphase input 132 and the output 134 of the operational amplifier 134. Since there are so many types of operational amplifier circuits, for example, LM324 or TL
A type of operational amplifier such as 084 may be used. The received signal enters the non-inverting input 136 of the operational amplifier through a pass band equalizer. The negative-phase input 132 of the amplifier is connected to the speaker / earphone 100, and the other end of the speaker / earphone is connected to the ground.

Since the current mirror shift of the operational amplifier 128 functions like a current source, the operational amplifier 128 receives the Rx signal at the non-inverting input and then transmits the Rx signal via the inverting input 132 to the loudspeaker. Transmit to earphone 100.
Since the antiphase input 132 is provisionally grounded, the voltage to ground is equal to about zero. This temporary ground does not reduce the current, and all the input current from the Rx signal is R1 (1
Flow through 30).

Therefore, the voltage gain of the amplifier 104 is -R
It is equal to 1 / Z1. A negative sign means that the phase of the input and the output of the operational amplifier are exactly opposite. The input impedance of the amplifier is Z
1, ie, equal to the impedance of the speaker and earphone 100. By using a unique method of driving the speaker / earphone 100 without load or shunting, the amplifier converts the electric signal (about 300 mV) from the audio input from the speaker / earphone into a signal with negligible signal loss. It is sent to the output 134 of the operational amplifier.

The amplifiers 106 on both sides of the differential amplifier arrangement
And 104 have a similar design. However, the speaker / earphone 102 has the opposite polarity to the speaker / earphone 100 on the other side of the differential amplifier arrangement, and the amplifier 106
Connect to This allows the differential amplifier 116 to amplify transmission signals from both sides of the differential amplifier arrangement by about one. As a point, a device such as an inductor may be used instead of the speaker and earphone 102 as described above. This device must match the impedance of the speaker and earphone 100 on the other side of the differential amplifier arrangement. When using matching impedance instead of speaker and earphone 102, there is only a received signal on this side of the circuit.
Therefore, the amplifier part in the compression / amplifier is not required.

The output signals of the amplifiers 104 and 106 are respectively supplied to the compression / amplifiers 108, 1 on both sides of the differential amplifier arrangement.
10 is transmitted. The compression / amplifiers 108 and 110 use a normal compander IC to compress a large received signal and amplify a small transmitted signal. When the received signal is amplified by the amplifiers 104 and 106, the received signal is one more than the transmitted signal from the audio output of the speaker / earphone.
5 to 30 times larger. Therefore, the compression / amplifiers 108 and 11
The proportionality between the received signal and the transmitted signal at the 0 output terminal reaches about 20: 1. On the other hand, using a compander IC, the ratio between the received signal and the transmitted signal is reduced to 6: 1. This compander IC compresses a received signal by a logarithmic function and amplifies a transmitted signal.

The differential amplifier 116 is a compression / amplifier (11
2, 114) to generate an output signal.
The transmission signal here is larger than the reception signal. Differential amplifier 1
16 is an operational amplifier 150 and resistors R3, R4, R5 and R
6 (152 to 158). The resistors R3 and R5 provide the output matching the compression / amplifier and the operational amplifier 1.
Connected between 50 two inputs. Resistor R4 is connected between one input and output of operational amplifier 150, and resistor R6 is connected between the other input and ground.

The large received signal is transmitted to the differential amplifier 116 in a common mode, and these signals are net canceled at the output, three times the original level at the input.
0 to 40 dB lower. Since the small transmission signals have opposite polarities, they are first amplified by the compression / amplifiers 108 and 110, and then further amplified by the operational amplifier 150. The output of operational amplifier 150 produces a combined transmit and receive signal. The transmitted signal portion of this composite signal is 20-30 dB larger than the undesired received signal.

The output signal of the differential amplifier 116 is transmitted to a horizontal transition circuit in the output stage 118. This horizontal transition circuit comprises resistors R7 and R8 (160, 162). This circuit is used to adjust the signal level of the output terminal of the other compression / amplifier 164. The special compression / amplifier 164 further amplifies the transmission signal and compresses the reception signal. Since the transmission signal level at this point is higher than that of the reception signal, a compression / amplifier 164 is provided in the output stage 118. The compression / amplifier 164 generates a signal above one reference threshold voltage level and also generates a signal below another reference threshold level. The horizontal transition circuit ensures that the input of the compression / amplifier 164 operates smoothly at a normal level.

The compression / amplifier 164 is an ordinary compander I
C is used. The compander IC can generate a larger delimiter between the Tx signal and the Rx signal. In this part of the circuit, the compander IC amplifies the difference between Tx and Rx, but in the input stage the compander IC
Reduces the difference between the Tx and Rx signals. Thus, by performing compression and amplification at the same time, the output signal has almost negligible small signals, that is, the transmission signal portion is about 30 to 40 dB larger than the reception signal portion. Therefore, the feedback of the reception signal to the transmission signal is almost canceled.

The output stage 118 has an automatic level control circuit 168. This circuit receives the output of the compression / amplifier 164 and adjusts it to an even output level.
For example, the transmission signal needs to be at a level of about -5 dB. Here, the automatic horizontal control circuit 168 is very effective.

The full-duplex communication circuit shown in FIG. 12 has various advantages. The special arrangement of the operational amplifier matching the speaker and earphone avoids any load or shunt on the speaker and earphone. For this reason,
The amplifier transmits a small electrical signal from the audio input to its output with negligible loss. Also, since there is no shunting of the received signal, interference between the received signal and the transmitted signal can be prevented, and the power of the received signal is reduced so as to be almost inaudible. Another advantage of this circuit is that since the compression / amplifier and the differential amplifier are used collectively, the received signal due to the output of the communication circuit is almost canceled. The compander IC and the differential amplifier simultaneously amplify the transmission signal and compress the reception signal, so that the feedback is almost canceled.

The front end of the full-duplex communication circuit shown in FIG. 13 uses a transistor to (1) drive a speakerphone having a reception signal from a remote source, and (2) a transmission signal generated by the speakerphone by audio input. Has the function of amplifying This received signal is passed through a pass band equalizer 25 for adjusting the balance of the signal frequency response.
0 is input to the circuit. The output of this pass band equalizer 250 passes through capacitor C1 (252). Resistors R1 (258) and R2 (254) form a voltage divider that supplies the required base voltage to transistor 256. The capacitor connects the output of pass band equalizer 250 to the input mode of the emitter arrangement of bipolar junction transistor 256.

The transistor amplifier comprises an NPN transistor 256 and four resistors R1, R2, R3, R4 (258,
254, 260, 262). This transistor amplifier is connected between the supply voltage Vcc and ground.
Resistor R1 is connected between the supply voltage and the base of transistor 256, and resistor R2 is connected between the base of transistor 256 and ground. The emitter is connected to the output of speakerphone 264 via resistor R4. On the collector side, the collector is connected to a matching impedance element or speakerphone 266 via a resistor R3. The collector side speakerphone or matching impedance element is connected between the supply voltage VCC and the resistor R3 (260).

Since the impedance between the collector and the emitter of the transistor is balanced, two matched outputs are formed at the collector and the emitter, each of which produces a received signal having a different phase. For the signal applied to the input of the emitter, the transistor operates like an inverter, so that the phase of the received signal at each output is different. If any of the inputs change, the resulting signal will all be included in the phase received signal. These signals are then provided to a differential amplifier and canceled. The matching impedance on the collector side is actually the speakerphone 264 on the emitter side.
Speakerphone or speakerphone 264 exactly the same as
May be used.

The communication circuit shown in FIG. 13 uses transistors as amplifiers in a shared emitter and shared base arrangement. For an arrangement having both a shared emitter and a shared collector, the current gain is equal to the current beta factor of the transistor. Similarly, for an arrangement with a shared emitter and a shared base, the voltage gain is equal to the quotient of the collector impedance and the emitter (Rc / Re). “Shared” in a bipolar transistor means that if the transistor terminal is an input terminal, it is also an output terminal.
That is, it means an input / output shared terminal. Therefore,
For a shared emitter arrangement, the emitter terminal is an input / output shared terminal. Of course, in a shared base arrangement, the base terminals are input / output shared terminals. In a shared emitter arrangement, the input node is the base of the transistor and the output node is the collector. In a shared base arrangement, the input node is the emitter of the transistor and the output node is the collector.

The transistor amplifier shown in FIG. 13 amplifies a received signal using a common base arrangement. Transistor 256 amplifies the current of the received signal provided to the base. The amount of amplification is equal to the current gain of the transistor. The voltage applied to the speakerphone 264 is approximately equal to the voltage of the received signal, ignoring the threshold voltage drop between the base and the emitter (about 0.7V) and the voltage drop across resistor R4.

The speakerphone 264 converts the audio output into a transmission signal at the output of the speakerphone. In a shared base arrangement, this transmit signal feeds the input of transistor 256. Therefore, this transmission signal gets a voltage gain equal to the voltage gain suitable for the shared emitter arrangement.

The transistor amplifier arrangement shown in FIG. 13 provided a method of effectively driving a speakerphone without a load. The electrical signal generated by the switch from the audio input is so small that the transmitted signal can be greatly reduced under any load on the speakerphone.

In FIG. 13, both outputs of the transistor amplifier are provided to opposite sides of the differential amplifier. The output of one side of the differential amplifier arrangement is obtained from the collector of transistor 256 and provided to inverter 270. When the inverter 270 inverts the transmission and reception signals, (1) the transmission signals on both sides of the differential amplifier arrangement undergo phase transition, and (2) the reception signals on both sides are in the same phase. As mentioned above, transistor 256 operates like an inverter, so transistor 256
The received signal at the collector has a different phase from the received signal at the base of the transistor. Therefore, the received signal output at the collector must be inverted so that the received signals are the same in magnitude and in phase on either side of the differential amplifier arrangement. The output on the other side of the differential amplifier arrangement is due to the output of speakerphone 264. At this output node, the received signal has the same phase as the received signal supplied to transistor 256, but undergoes a phase transition with respect to the output of the collector of transistor 256. The transmission signal from the speakerphone 264 has the same phase as the transmission signal at the transistor output.

The composite transmit / receive signal at the speakerphone output is
It is provided to a linear amplifier 272 having a gain equal to the gain of inverter 270. This linear amplifier 272
Amplifies the transmit / receive composite signal and provides its output to the other side of the differential amplifier arrangement.

The inverter 270 includes an operational amplifier and a resistor R
4, R5, R6 (276, 278, 280) are used.
The gain of the inverter is equal to R5 / R4. The linear amplifier 272 has a similar configuration. However, the output is supplied to a non-inverting input of the operational amplifier 290. Linear amplifier 2
72 is an operational amplifier 290 and three resistors R7, R8, R9
(292, 294, 296) and the gain is R8
/ R7.

The outputs of both the inverter 270 and the linear amplifier 272 are supplied to the differential amplifier. The differential amplifier adds the transmitted signals on each side and cancels most received signals. To achieve good performance, the outputs of the inverter and the linear amplifier are provided to two similar compression amplifiers that simultaneously compress the received signal and amplify the transmitted signal. As a specific method, the outputs of the inverter and the linear amplifier are compressed at nodes A and B as shown in FIG.
Supply to amplifiers 108 and 110. Other parts of the present communication circuit are the same as the circuit shown in FIG.

The handset 2 is connected to the speakerphone 20 (40 and 4).
2, 60 and 62, 100 and 102, or 264) and a full-duplex communication circuit as shown in FIG. 9, 10, 11, 12, or 13, so that FIG. The handset 2 can be in the form of a normal earphone. Therefore, a call can be made while the handset 2 is hung on the ear.

The speakerphone 20 (40 and 42, 60 and 6
It is desirable to use a bone microphone for the microphone of 2, 100 and 102 or 264). As a result, the human voice resonates with the skull and becomes a very good voice, and can talk under any noise.

Further, by using the handset 2 that can be inserted into the ear, instead of pressing the function button of the telephone body 1 when operating the telephone body 1,
You can also operate by voice. For example, chewing the back teeth twice can be regarded as the start of reception, and chewing the back teeth three times can be regarded as the end of the call.

On the other hand, in the telephone body 1, mounting members 11, 12 for attaching the telephone body 1 to the arms at both ends.
Is provided. In the present embodiment, the fixtures 11, 1
Reference numeral 2 denotes a band 15 which is attached to an end of the telephone main body 1 with a metal fitting 15. At both ends of the band 14, magic tapes 13, 13 are provided. Phone body 1
The liquid crystal display unit 1a may be used as a monitor of a telephone and a display unit of a digital clock. Therefore, the telephone body 1
Is not only a telephone but also a clock.

The telephone body 1 and the transmitting / receiving device 2 communicate with each other wirelessly or by wire. When using the telephone, as shown in FIG. 3, the telephone main body 1 is attached to the user's arm via the attachments 11 and 12, and the handset 2 is attached to the user's ear.

[0064]

Second Embodiment FIG. 4A is a perspective view showing a structure of a telephone apparatus according to a second embodiment of the present invention, and FIG. 4B is a view showing a state in which the telephone body is covered by a cover. is there. According to FIG. 4 (a), the telephone device of the present invention comprises a portable telephone body 3 and a handset 2 (FIG.
Reference). The telephone main body 3 is a telephone device main body, which is attached to a user's arm. The handset 2 is exactly the same as that shown in the first embodiment.

The telephone body 3 is shaped like a sports watch, and has a wristband 31 attached.
Further, the liquid crystal display unit 30 of the telephone body 3 may be used as a display of a digital clock as well as a monitor of the telephone. Thus, a telephone is not only a telephone but also a watch. When such a telephone 1 is used, as shown in FIG.
Using the wristband 31, the telephone main body 3 is attached to the user's arm, and the handset 2 is attached to the user's ear.

Further, it is desirable to provide a cover 4 for the telephone body 3. As shown in FIG. 4B, the cover 4 includes a storage section 41 for storing the telephone body 3 and a lid 47 for closing the opening of the storage section 41.
Are connected by a chuck 43. The cover 47 has an opening 45 so that the liquid crystal display 30 of the telephone body 3 housed in the cover 4 can be seen. Therefore, the liquid crystal display unit 3
Since 0 is visible even with the cover 4 attached, it is very convenient to use the telephone main body 3 as a clock except during a call.

[0067]

Third Embodiment FIG. 6 is a perspective view showing a third embodiment of the present invention. The telephone device shown in FIG.
And the method of use is exactly the same, except that the telephone body 3 in the embodiment is shaped like a sports watch, whereas the telephone body 5 in the embodiment is a normal watch. It has a shape. The wristband 51 is exactly the same as the wristband 31.

[0068]

Fourth Embodiment FIG. 7 is a perspective view showing a fourth embodiment of the present invention, and FIG. 8 is a diagram showing a use state of the telephone device of FIG. According to FIG. 7, the telephone device of the present invention comprises a wristwatch-type telephone body 7 and a handset 2 (see FIG. 2) for wirelessly communicating with the telephone body 7. A wristwatch 8 (analog or digital clock) connected to the camera 7 is attached.

When such a telephone device is used, the telephone device shown in FIG.
As shown in FIG. 8 and FIG.
Is attached to the user's arm with the belt 81. The distance between the telephone body 7 and the watch 8 is adjusted via the belt 9. Also, as in the above embodiments, the handset 2
To the ear. In such a telephone device, the telephone body 7 and the clock 8 are connected to each other and attached to the arm, so that the user can have a good image and the use of the telephone and the clock is convenient.

The present invention is not limited to the first to fourth embodiments. For example, the telephone body can be not only a mobile phone but also an ordinary stationary phone. The telephone body may be a telephone main unit as well as a telephone main unit.

[0071]

As is apparent from the above description, according to the present invention, since the full-duplex communication circuit used in the telephone has neither voice feedback nor electric feedback, the handset can use both a speaker and an earphone. Thus, the user can put the handset on his / her ear and talk.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a telephone main body of a telephone device according to Embodiment 1 of the present invention.

FIG. 2 is a perspective view showing a handset of the telephone device according to Embodiment 1 of the present invention.

FIG. 3 is a perspective view showing how to use the telephone device according to FIGS. 1 and 2;

4A and 4B illustrate a telephone device according to a second embodiment, in which FIG. 4A is a perspective view illustrating a structure of a telephone body, and FIG. 4B is a diagram illustrating a state in which the telephone body is covered by a cover.

FIG. 5 is a perspective view showing how to use the telephone device of FIG. 4;

FIG. 6 is a perspective view showing a telephone device according to Embodiment 3 of the present invention.

FIG. 7 is a perspective view showing a telephone device according to Embodiment 4 of the present invention.

FIG. 8 is a perspective view showing a method of using the telephone device of FIG. 7;

FIG. 9 is a block diagram of a full-duplex communication circuit used by the telephone device according to the first embodiment;

FIG. 10 is a block diagram of another full-duplex communication circuit used by the telephone device according to the first embodiment.

FIG. 11 is a block diagram of another full-duplex communication circuit used by the telephone device according to the first embodiment;

FIG. 12 is a detailed diagram of a full-duplex communication circuit used by the telephone device according to the first embodiment.

FIG. 13 is a detailed diagram of another full-duplex communication circuit used by the telephone device according to the first embodiment.

[Explanation of symbols]

 1, 3, 5, 7 Telephone body 1a Liquid crystal display unit 2 Handset 4 Cover 9 Belt 11, 12 Fixture 13 Magic tape 14 Band 15 Metal fittings 22 Amplifier 24 Compression / amplifier 30 Liquid crystal display unit 31 Wrist band 40, 42 Speaker and speaker Earphone 41 Housing 43 Chuck 45 Opening 47 Cover 48 Differential amplifier 51 Wristband 68 Compression / amplifier 70 Compression / amplifier 71 Belt 72 Differential amplifier 100 Speaker / earphone 102 Speaker / earphone 104 Amplifier 106 Amplifier 108 Compression / amplifier 110 Compression -Amplifier 112 Output terminal 114 Output terminal 116 Differential amplifier 118 Output stage 120 Final transmission signal 122 Input reception signal 124 Pass band equalizer 126 Output 128 Operational amplifier 130 Resistance R1 132 Negative phase input 134 output 136 non-inverted phase input 150 operational amplifier 164 compression amplifier 168 automatic level control circuit 250 pass band equalizer 252 capacitor C1 254 resistor R1 256 transistor 258 resistor R2 260 resistor R3 262 resistor R4 264 speakerphone 270 inverter 276 resistor R4 278 Resistance R5 280 Resistance R6 290 Operational amplifier 292 Resistance R7 294 Resistance R8 296 Resistance R9 VCC Supply voltage

Claims (15)

[Claims] In a telephone apparatus comprising a telephone body and a handset connected to the telephone body, the handset converts an audio input into an electric transmission signal and simultaneously converts an electric reception signal indicating audio data into an audio output. And a compression / amplifier for communicating with the first speakerphone is provided. The compression / amplifier receives a composite signal including the transmission signal and the reception signal, and converts the transmission signal. Amplify and compress the received signal so that the transmitted signal is at least one more than the received signal
A telephone device for generating an output signal that is 0 times larger. 2. A matching method for matching the impedance of the first speakerphone and receiving the received signal.
2. The telephone device according to claim 1, further comprising an impedance element, a compressor connected to the matching impedance element, and a differential amplifier connected to the compression / amplifier and the compressor. 3. The matching impedance element is a second speakerphone that converts an audio input to a second electrical transmission signal and converts the electrical reception signal to an audio output, and wherein the compressor is a second compression amplifier. And is connected to the second speakerphone,
The telephone device according to claim 2, wherein the differential amplifier is connected to the second compression / amplifier. 4. The first speakerphone is connected to a linear amplifier for transmitting a received signal to the first speakerphone without applying a load to the first speakerphone. Telephone equipment. 5. The linear amplifier uses an operational amplifier having a non-reversing input and a reversing input, the non-reversing input receiving the reception signal, the reversing input being connected to the first speakerphone, and 5. The telephone device according to claim 4, wherein the linear amplifier transmits a received signal to the speakerphone by the reverse input without applying a load to the speakerphone. 6. The telephone device according to claim 1, further comprising a two-way transistor for driving the speakerphone with the received signal and amplifying a transmission signal from the speakerphone. 7. The transistor has a base, a collector and an emitter, the base receiving the received signal, and the speakerphone being connected to a matching impedance element connected to the emitter and the collector. 7. The telephone device according to claim 6, wherein: 8. An inverter connected to the collector, an amplifier connected to an output of the speakerphone between the speakerphone and the compression / amplifier, and connected to the inverter for compressing the received signal. A compression amplifier; and a differential amplifier connected to the compressor / amplifier, the differential amplifier receiving the composite signal from the compressor / amplifier and the received signal from the compressor. 8. The telephone device according to claim 7, wherein said received signal is almost canceled. 9. The telephone device according to claim 1, further comprising an output stage for receiving an output signal of the compression / amplifier, amplifying the transmission signal, and compressing the reception signal. . 10. The speakerphone according to claim 1, wherein the speakerphone is a speaker / earphone.
The telephone device according to 6, 7, 8 or 9. 11. The speakerphone according to claim 1, wherein the speakerphone is a speaker / microphone.
The telephone device according to 5, 6, 7, 8 or 9. 12. The telephone device according to claim 1, wherein the telephone body is a telephone device main body. 13. The telephone device according to claim 1, wherein said telephone main body is a telephone main unit. 14. The telephone device according to claim 1, wherein the telephone body is a telephone handset. 15. The telephone device according to claim 12, wherein the telephone body is attached to an arm.